Briggs Intek V-Twin(s) Blowing Sump Gaskets....

BriggsGalaxiemanDecember 12, 2012

Engine: Briggs Intek V-Twin 26 hp 446777-0244-E1

I am having a problem with blowing out sump gaskets on this model engine. Twice it has happened on two different engines:

1. My original factory 446777, purchased in 2004, developed the sump gasket leak after about 8 years use. I replaced that gasket using RTV Blue as a sealer and it does not leak (so far).

2. I rebuilt a second 446777 for another tractor, about two years ago. This engine developed the exact same leak last summer. The picture below shows this engine that I just now disassembled. The picture shows the damaged gasket exactly as it appeared when I opened the sump.

In both engines the leak was in exactly the same place (directly below #2 cylinder). The original 2002 factory engine did not have any sealer on the gasket (as I used on both gaskets I replaced), but it did fail in exactly the same place.

Any ideas?


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I personally would not use silicone. When I do these, they get a light amount of high tack on the gasket before it is installed. Do both sides if you wish. Any signs of loosening on the fasteners, use loctite- or maybe use it anyways.

    Bookmark   December 12, 2012 at 10:00AM
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I don't think the problem is with the silicone because I had the same leak...same place with the factory no gasket setup...and I have another engine that I did with silicone that does not leak....

The first thing I have checked when leak started was the bolts. Never found one untight. I used a torque wrench on all sump bolts when assembling....

    Bookmark   December 12, 2012 at 10:39AM
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did the gasket blow out - or was it sucked into the crankcase?

    Bookmark   December 12, 2012 at 10:58AM
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The gasket was exactly as you see in the photo. The one small piece was hanging outside of the engine before I took it apart. I did not touch that area of the gasket when removing the sump. But, the other 'half' of the gasket was inside the sump as seen in the photo.

It actually appears to have been 'blown out' AND been 'sucked in'....

    Bookmark   December 12, 2012 at 12:13PM
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A certain brand of forklift transmission where I work will have a control valve gasket failure (blow out) of the OEM gasket at the main pressure galley which will result in transmission slippage upon takeoff.
The reason the gasket fails is due to the ultra smooth surfaces of both the trans case (cast iron) and the control valve (cast aluminum alloy). The aluminum casting process used by the OEM produces such a perfectly smooth gasket surface that they don't even machine the gasket perimeter at all. And the "too smooth" surface is what leads to the failure of the OEM gasket after about 10,000 hours on the clock (approx. 3 years in our operation) because there is no "tooth" on the metal surface to bite into the gasket surface and hold it in place.
My fix which I learned years ago working in a motorcycle shop (where we had a similar problem on engine valve covers) is to first clean off all oil using a shop towel wet with spray carb cleaner (or other volatile solvent) and lightly scuff the entire gasket perimeter with a Scotchbrite pad.
Next, using an automatic center punch I make a line of punch upsets at about the centerline of the gasket perimeter about 3/8" to 1/2" apart around the entire gasket line.
Lastly, after marking which side of the new gasket will be in contact with the punched surface, I spray that surface of the GASKET with Permatex High Tack gasket sealer/adhesive. Then while the High Tack is still wet, I flip the gasket over and lower it into position on the valve body. Get all the bolt holes aligned and press the gasket down evenly. Then I install the valve to the trans case and torque to specs.
Have not had a repeat failure in 12 years of doing this.
I am having to resort to using 3 separate posts for the photos as the forum does not seem to want multiple image uploads (er else I ain't figgered it out yit).

    Bookmark   December 12, 2012 at 1:03PM
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Photo 2

    Bookmark   December 12, 2012 at 1:04PM
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Photo 3

    Bookmark   December 12, 2012 at 1:05PM
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Galaxyman, I believe if you use my technique you will have success in holding the gasket in place.
And silicone RTV is not the preferred sealant to use on aluminum surfaces unless it is especially formulated for aluminum.
And even when you use RTV that is compatible with aluminum (the Permatex ULTRA line in any color)) you must clean the surfaces well with an evaporating type solvent.
The last (and maybe most significant in your failures here) is that some GASKETS will not bond to ANY formula of RTV.
I always use High Tack when I go with a gasket.
RTV of the correct type can often be used INSTEAD OF a gasket in certain applications, but a sump gasket is not one of those places because the thickness of the gasket is accounted for in the end spacing clearance of the crankshaft bearings.

    Bookmark   December 12, 2012 at 1:16PM
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As usual...really good information!

Yes, the gasket surfaces are both aluminum, very smooth and shiny!

Your suggestion to 'rough up' the surfaces makes a lot of sense. After that, I will follow up with a lacquer thinner cleaning and High Tack sealant with the gasket.

I suspect that the failure of the gasket in that particular place, on this engine, is caused by heat.

If you look again at my picture you can see that the problem area for the gasket on this engine is right below #2 cylinder bore. The #2 cylinder bore is within about 1/2 inch of the gasket failure. That, it seems to me, would be a place that gets extra hot. The #1 cylinder bore is offset vertically and 1 1/2 inches from the gasket surface. The 'extra' heat on the gasket area may cause just a 'little bit extra' expansion of the joint between the surfaces and thus allow the gasket to 'slip' on the smooth surfaces. Since the sump is under positive pressure it would tend to push the gasket outward, which did happen here.

Thanks for your help,


    Bookmark   December 12, 2012 at 3:20PM
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BGM, that is entirely possible. By the way, Permatex has a "brush in can" version of High Tack which I have used at home. Mainly I like the brush/can because there is no overspray with it, and I can tell you that the spray type will make some pretty spider webby looking red overspray if ya ain't real careful. That is why I spray it on the gasket at work instead of the metal surface. I can put the gasket on a scrap piece of cardboard and spray away without painting everything nearby. :^)

    Bookmark   December 13, 2012 at 12:02AM
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I had planned to pick up some Permatex High Tack (brush in the can style) at my local parts store. I just noticed that I do have Permatex Super 300 Form-A-Gasket 'in stock'. Would that be OK for the sump gasket or should I get the Permatex High Tack?

Thank again,


    Bookmark   December 13, 2012 at 10:36AM
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Well, I'm gonna be opinionated on that one. I went to the Permatex website and reviewed the corporate blurbs. While the 300 and the High Tack do read very similar.....only the High Tack had any verbage about "holding a gasket in place".
Both products purport to "seal" but only the High Tack mentioned "holding", and even THAT might mean "during assembly".
Possibly either of the products could provide a decent and dependable bond given the metal surfaces are prepared properly by scuffing and de-oiling with an evaporating solvent prior to assembly.

    Bookmark   December 13, 2012 at 11:03AM
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I thought I would tie up this thread by showing what I did for the sump assembly:

First, I roughed up the gasket surface on both the sump and block with a small wire brush in a drill. The 'scratching' is just enough so that I can feel it with a fingernail.

Then, I punched slightly raised marks onto the gasket surface of the sump with a punch and hammer.

Then, I finshed the assmebly using Permatex High Tack Gasket Sealant:

Hopefully this will finally solve my gasket blowout problems. Thanks for the suggestions....


    Bookmark   December 23, 2012 at 5:55PM
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Well sir, I believe that will do the trick. :^)

    Bookmark   December 23, 2012 at 6:22PM
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I am just catching up with the various comments and the job may be completed, but here are more comments.

In the original picture, my impression is the gasket was crushed at the bolt hole. Perhaps the factory overtorqued and part of the gasket was pushed in and part of the gasket was pushed out. i don't know if extreme engine heat may have caused this. Another possibility is full torque may have been applied to the one bolt before the other bolts were screwed down.

When evaluating this type of problem, a straight edge should be placed across the bolt holes to see if there is any warpage. This type of damage would apply excessive pressure to the gasket around the bolt holes. The space between the bolt holes may not apply enought pressure to hold the gasket in place. Since the crankcase is supposed to operate with slightly negative pressure, a gasket that is not securely held in place would most likely be sucked into the crankcase.

hopefully the suggested repairs will solve the problem. After assembling and starting the engine, consider performing a crankcase vacuum check.

    Bookmark   December 25, 2012 at 12:13AM
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I joined this site just so I could post a follow-up to this thread.

I had the exact same issue posted above and I tried the same fix, it lasted all of about 45 minutes before the gasket failed again.

It's odd that it's actually "sucking" the gasket into the engine as though there were too much vacuum.

I think there could be something to the rumor that the sump bolts are too long, creating less torque in that area.

This time I put it back together, I intend to get some new bolts that are a few mm shorter, and use a tap to clean out the threads.

I am going to use some grey silicone this time instead of the high-tack, although I haven't decided if I am going to coat the paper gasket with it, or simply use it to create a gasket. I'm leaning towards the former.

    Bookmark   June 2, 2014 at 12:29PM
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It is not recommended to "SUBSTITUTE" RTV for a gasket in this application BECAUSE the thickness of the gasket itself is factored into the crankshaft and camshaft "end play" dimensions.
If the gasket is omitted entirely and RTV only is used to seal the sump, the crankshaft and camshaft will have LESS than the specified amount of end play for the 2 shafts mentioned.
If you did the pin prick trick along the gasket perimeter, some other error must have had an effect on your new gasket moving like it did.
And, I don't know if you used genuine High Tack or a wannabe look similar product.
I have never had a repeat failure on a sump gasket using the exact methods described in the thread.

    Bookmark   June 2, 2014 at 1:11PM
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Yes, I agree with mownie...his method of pin pricks and high tack worked for leaks in the year and a half since repair.....:-)

    Bookmark   June 2, 2014 at 2:56PM
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Yep, genuine Permatex high tack, plus I roughed up the surfaces and peened them.

    Bookmark   June 2, 2014 at 2:58PM
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Well, the above fixes lasted about 8 hours of runtime but its back to leaking like crazy again.

It frustrating because I was so meticulous this time, cleaning out the threads, using new bolts, red thread locker, and torqued the to spec.

It seems to happen after the engine is suddenly put under high stress, like a tall patch of grass.

Anyone have any ideas? I'm at my wits end.

Its enough to permanently sour me to Briggs and Stratton.

    Bookmark   July 12, 2014 at 4:04PM
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On a repeat fail scenario (which I have not yet encountered) I would have to ask, are the 2 hollow dowels still in place at 2 bolt hole locations, or have the dowels been discarded?
The 2 dowels are absolutely necessary because the bolts themselves are only there to provide CLAMPING force to pull the sump cover and the crankcase together.
The dowels provide a precision fit of the sump and crankcase AND ALSO deal with the torsional shear loads that exist between the sump and the crankcase when the engine is operating.
If 1 or both of the dowels are missing from the bolt pattern, there WILL BE some shear load that will be directed into the gasket itself, and the gasket was not designed to deal with shear loads.
The engine design is that the dowels keep the sump and crankcase from having any relative movement between them.
So, do you still have 2 dowels in place?

    Bookmark   July 12, 2014 at 4:22PM
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Yes, the 2 dowels are still there. I haven't pulled it back apart yet as the engine is still hot, but at this point I don't know if its worth my time... A new mower wasn't in the budget this year though.

    Bookmark   July 12, 2014 at 4:27PM
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I've not had one of these come back either. I can tell you that it can be problematic to reseal a sump that has worked loose however. Back when they had singles that would do that in 94 ish models I had 2 bite me in the bum and if they are loose and hunting- I don't reseal with any guarantee. If you started with the typical breaking of the gasket and the sump was basically secure, one would hope it to reseal. I can tell you that the part number changed over the last year. Which number gasket did you use out of curiosity? If I had to do one over, I'd find a creative way to use Right Stuff and it shouldn't leak as long as it holds together. Should you pull it down, let's see where the leak was, if it kicked the gasket out again etc. One wouldn't think that the sump gasket would be the first to go if it was building pressure or vacuum... Any abnormal vibration?

This post was edited by tomplum on Sat, Jul 12, 14 at 18:56

    Bookmark   July 12, 2014 at 6:51PM
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The first gasket was in the kit that I got here:

The second gasket I picked up locally, but I believe it was pn#: 697227

The engine does have a lot of end play in the crank. I didn't measure it, but I believe it is close to what is considered the max. Omitting the gasket entirely should help this shouldn't it?

I don't understand how there can be enough pressure or vacuum in the crankcase to blow out these gaskets. The black tube running from the crankcase to the plastic intake is the pcv right? Is there a check valve in there somewhere?

The engine runs great otherwise...there might have been a slight drop in power just prior to this happening, but its hard to tell as I was mowing pretty tall grass.

    Bookmark   July 13, 2014 at 11:29AM
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It would be a good idea to measure the end play. They can be as slight as .002 or .003 yet up to .030" . I don't recall seeing anything when they updated the gaskets. The new number doesn't look to be anything super special, though it is white in color. Maybe it is stronger than the more fibrous one that you last installed. 591911 is the latest number. I see that the sump part number has changed, though I dunno why. The breather has a reed type valve in it and should basically not be distorted. They are cheap to replace for that matter if you are concerned. You didn't seem to post the numbers from your engine, but if it is old enough to have a breather gasket- inspect that it isn't leaking or there are any other leaks such as a dipstick seal or ring. if you pull the breather, either reseal w/ right stuff or get a new gasket.

    Bookmark   July 13, 2014 at 3:59PM
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The engine is a model # 445877

I got it back apart this evening. You can see the failure just to the left of the oil filter.

I went ahead and bought some Right Stuff, although at this point I am not convinced that it will last, something has to be causing excessive vacuum in the crankcase.

    Bookmark   July 14, 2014 at 12:17AM
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Think of things along that path then. What has the breather inspection told you? Have you a straight edge to check the block and the sump? That edge kinda could be like bad news if it broke the gasket at both holes like that. Is that grey sealant on a white gasket? My Hi tack is purple or red depending on which I use. If you rely only on the Right Stuff sealant, you will need to do a fit first to check your end play. Not too sure that that in itself is a good idea...

    Bookmark   July 14, 2014 at 1:34AM
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My thoughts exactly on the lack of color confirming High Tack.
I have also learned in my 40+ years as a mechanic that using any kind of sealant or bonding agent is to be approached with "caution".
The caution part is that a liquid or semi-liquid product must be used only as instructions for the product call out. Read on.
The gasket in the photo failed at 2 bolt holes. The nature of the failure here is due to "hydraulic pressure" created when the gray RTV was squeezed from the seam as the bolts were tightened.
Essentially, the gasket was ejected from the seam by being carried along with the RTV and the gasket actually failed when the bolts were torqued.
This is not conjecture, I have seen this type of failure over the years where RTV was used.
There are 2 reasons why this kind of failure occurs when RTV is used in conjunction with a gasket.
1. The surfaces where the RTV is applied were not cleaned thoroughly with an "evaporating solvent" such as spray carb cleaner or lacquer thinner and allowed to dry completely before applying the RTV. If any trace of oil or grease remains on the application surfaces, the RTV will not "adhere" to the surface but will instead flow out of the seam en masse when clamping torque is applied.
2. Applying too much RTV. Putting too much RTV on the surfaces (even if they have been properly de-oiled) will result in "hydraulic ejection" with the potential to move the gasket right along with it.

Consider this when looking at the photo.
The gasket failed by tearing/breaking at holes (at 2 bolt hole locations). This means that the gasket was already being ejected BEFORE the bolts reached full clamping torque.

The amount of RTV I see in the photo DOES NOT appear to be excessive, so I am going to surmise that the surfaces were tainted with oil film which resulted in the RTV ejecting the gasket when the sump bolts were torqued.
When it comes to RTV, cleanliness is next to "goodliness" (yes, that was spelled as intended).
RTV has its places in automotive repair (and other fields), but this is not the place to be using RTV.

Clean that up and de-oil using an evaporating solvent.
Make some new prick punch marks AFTER using the evaporating solvent.
Use Permatex High Tack (brush in can or spray version).
Allow the High Tack to "flash off" (evaporate) according to the product instructions. High tack does not require assembly of parts while it is still "wet", in fact it will work better if it is allowed to lose some of its solvent base through evaporation before the halves are mated together.

This post was edited by mownie on Mon, Jul 14, 14 at 12:02

    Bookmark   July 14, 2014 at 8:48AM
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I cleaned thoroughly both times with carb cleaner and a wire wheel. I was very meticulous in this regard.

The first time I did it, I used the High Tack, and it only lasted about 45 minutes. The silicone did hold for about 8 hours.

I guess its possible that that area of the gasket was tainted with oil during assembly both times. I also failed to realize that Briggs has a specific tightening pattern for the sump bolts, although I did torque them evenly.

I'm going to clean it up and do a dry fit with no gasket and see what the end play feels like. I haven't inspected the vent yet.

    Bookmark   July 14, 2014 at 9:24AM
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I have the same issue and replaced the gasket and seal. I must have done something wrong when putting it back together. It will only run full throttle. I assume something to do with the governor either internally in the sump or the linkage outside. However I disconnected the linkage and it still does it. I thought I put it back the same as it came out but apparently not. Any ideas on how can I fix it ?

    Bookmark   July 15, 2014 at 9:10PM
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I didn't realize that these engines were setup this way until recently, but I think what the throttle is actually doing is keeping the governor from opening all the way.

On mine, there was a very faint scratch/discolored area on the shaft that i lined up with the crack in the governor arm.

    Bookmark   July 16, 2014 at 10:12PM
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Well I did a dry fit of the sump with no gasket at all and there is still some discernible end play in the crank so there should be no issue there.

So at this point I have 2 options, either get a new paper gasket and put it in dry (which I'm not optimistic about) or omit the gasket and just go with the "Right Stuff".

I'm leaning towards the latter at the moment.

Did I mention I really appreciate you guy's input and opinions?

    Bookmark   July 18, 2014 at 12:46PM
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I say go for it then. It is awesome stuff. I personally have not sealed a small engine sump, but have on plenty of other pans and covers. Even did a tire repair on a rider that was meant to be temporary that lasted using a plug and this stuff. You could be blazing a new trail here, be it not according to the Briggs Gods. Get a feeling for how it works first, because you don't need very much. When done, be extra watchful after it is done to confirm that you had a good repair. We expect a full report.

    Bookmark   July 19, 2014 at 11:30AM
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Well I got it all cleaned up and re-sealed using only the Right Stuff. You were right, this stuff is definitely harder than silicone, so I'm hoping this will hold up. My only concern is that a piece of it comes loose and blocks an oil passage.. but at this point any more time I can get out of this engine is a bonus. It's been curing now for about 4 days so I hope to get it buttoned up and run it today.

I inspected the crankcase vent and everything looks good there, but I am going to go ahead and replace the vapor collector just to be on the safe side.

I did also get a little more aggressive with the wire wheel on the surfaces. I noticed this time some scalling, or pitted areas on the cooling fins of the cylinder directly above the problem area, so this tells me there is something that happened there.. maybe it got too hot? although I can't see how.

    Bookmark   July 26, 2014 at 11:50AM
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This stuff doesn't let go too easily. In theory, you could clean the outer area by the blow out and put a ribbon of the stuff over the seam. I had a Kawasaki twin that had a similar condition that the guy begged if I could do a temp fix so he could mow lawn until I got back to working on his. All I did was remove the cooling tin, cleaned it up and dabbed some on the outside and it stayed sealed.

    Bookmark   July 26, 2014 at 12:30PM
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Well so far so good, I mowed with it for about 3 hours and the seal held up. There is a noticeable loss of power though that i cant explain. Maybe the governor is out of adjustment?

    Bookmark   July 28, 2014 at 9:19AM
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Could be. I did one of these Friday and was wondering how you turned out. Keep us in the loop. When ever I give an estimate on these, I make clear what they are paying for. I've done sumps that, when you invert the engine- crud comes out of the float bowl and starts to plug up the nozzle.The runabilty isn't quite the same , so carb work gets added on. Could be the case too.

    Bookmark   July 28, 2014 at 8:30PM
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larso1(So. CO Zone 5)

Hmm, has no-one used Loctite 515 Plastic Gasket for mating steel surfaces? Is an anaerobic curing plastic gasket recommended for the joint on Norton Commandos (for one) between the joint of the cylinders and the crankcase. I've never had a leak there, and there are a lot of reciprocating forces between the cylinder and the crankcase on a Norton.

Here is a link that might be useful: Loctite 515 Plastic gasket

    Bookmark   July 29, 2014 at 9:19PM
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tojoski- Any more news on your repair?

    Bookmark   August 23, 2014 at 12:21PM
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So far, the seal I made using only The Right Stuff is still holding up.

One day there was some oil that had dripped down on the pulleys, but It didn't come from the sump seal. I cleaned it off and it hasn't been back. I changed the oil pump seal and the crank seal the first time I had it off.

At this point I am a believer in The Right Stuff.

    Bookmark   September 13, 2014 at 4:07PM
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Thanks for the update. Continue to do so.

    Bookmark   September 14, 2014 at 1:31AM
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Another update to the sump saga. A new kit 594195 is for resealing the sump on these. It looks to be the same white gasket that was in parts a year ago, but it includes new bolts dressed w/ loctite and specific instructions for installation. The sequence feels the same, except torque has been increased to 300 inch pounds. That is after cleaning, chasing and installing their new bolts.

    Bookmark   October 7, 2014 at 6:49PM
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Thanks for the update Tomplum....

Wow! Torque spec up 50% from 200 in/lbs to 300 in/lbs. Maybe that will help...after all the rest of the prep.

    Bookmark   October 8, 2014 at 6:23AM
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