'91 Evo bad case stud
Thread Starter
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Cruiser
Joined: Sep 2010
Posts: 178
Likes: 0
From: Albany, Oregon
'91 Evo bad case stud
I just had my engine gone through. 9.5-1 compression, Andrews 46 cam, Baisley heads.
After 800 miles, I blew a front head gasket. Upon disassembly, I found one of the studs had pulled after a poor helicoil job. I bought the TimeSert repair kit, and I'm sure that will save this case.
My question is: Do I need to do all the other studs as well? The prior owner had installed Delkron studs, and all the others are tight as can be. I don't want to repair them if I don't have too, but am I better off doing the others now, or can I trust them?
Advice is greatly appreciated.....
After 800 miles, I blew a front head gasket. Upon disassembly, I found one of the studs had pulled after a poor helicoil job. I bought the TimeSert repair kit, and I'm sure that will save this case.
My question is: Do I need to do all the other studs as well? The prior owner had installed Delkron studs, and all the others are tight as can be. I don't want to repair them if I don't have too, but am I better off doing the others now, or can I trust them?
Advice is greatly appreciated.....
Tourer
Joined: Jun 2008
Posts: 306
Likes: 7
From: Somewhere, PA
If it were me and all the others are nice and tight, I wouldn't mess with 'em. It's different if I'm opening up the cam chest to change the old INA bearing to a Torrington, 'cause then you might as well change the cam, etc. while you're in there. With the studs, I look at it a little differently since they USUALLY don't cause that much grief...
My .02
My .02
Seasoned HDF Member
Joined: Nov 2009
Posts: 15,706
Likes: 22,728
From: Farmington ,MS
Just make sure the case is not cracked...the middle two on the cam side are notorious for cracking.
https://www.hdforums.com/forum/evo-c...-1990-evo.html
https://www.hdforums.com/forum/evo-c...-1990-evo.html
Club Member
Joined: Apr 2011
Posts: 5,827
Likes: 7,852
From: SE Louisiana
PacMul, where to buy the timesert repair kit? I have the same problem with a heli coil not holding the torque through heat cycles and pulling out.
With having a helicoil already installed, is the timesert OD big enough?
With having a helicoil already installed, is the timesert OD big enough?
Thread Starter
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Cruiser
Joined: Sep 2010
Posts: 178
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From: Albany, Oregon
I just got the Time Sert today. I bought it from www.threaddoctor.com. They're on ebay too.
It is larger OD than the helicoil. That means there is some meat left to drill (just a little) and then re tap to install TimeSert.
I went this route originally because of a friend who works for GM. He really insisted that the TimeSert is stronger. They use them for Cadillac spark plug threads that are prone to failure, so he had hands on experience.
Once they got here, the insert part does seem much stronger made. It just looks beefier.
Thanks for the advice everyone. I'm going to leave the existing studs alone and do them all next time the motor is open. I wish I had done them while the motor was open, but I'm not looking back now.
I'll let you know how it goes...
It is larger OD than the helicoil. That means there is some meat left to drill (just a little) and then re tap to install TimeSert.
I went this route originally because of a friend who works for GM. He really insisted that the TimeSert is stronger. They use them for Cadillac spark plug threads that are prone to failure, so he had hands on experience.
Once they got here, the insert part does seem much stronger made. It just looks beefier.
Thanks for the advice everyone. I'm going to leave the existing studs alone and do them all next time the motor is open. I wish I had done them while the motor was open, but I'm not looking back now.
I'll let you know how it goes...
Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
My Velocette Thruxton had a similar problem of blowing its head gasket, which I cured with a helicoil on the one stud only. Obviously in your case the spoiled helicoil has to go, so please let us know how the Time Sert goes. Some pics will be interesting!
I started my working life manufacturing aircraft engines. They use helicoils throughout during manufacture (and silver-plated screws at the hot end!), but plainly don't have the cyclic loading an internal combustion engine gives them. So while we may see helicoils as a repair item that is not their original application.
I started my working life manufacturing aircraft engines. They use helicoils throughout during manufacture (and silver-plated screws at the hot end!), but plainly don't have the cyclic loading an internal combustion engine gives them. So while we may see helicoils as a repair item that is not their original application.
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Club Member
Joined: Apr 2011
Posts: 5,827
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From: SE Louisiana
PakMul, did your kit come with a tap guide?, looks like the ebay set (5381D) comes with one. Also, what stud to use, the original with the intrference fit, might be very hard to screw in, and might try to gall, or is there one I can buy without the interference fit and not have to buy a whole set.
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Stellar HDF Member
Joined: Apr 2009
Posts: 3,039
Likes: 11
From: Northern Ontario
I had this problem last summer and I installed timeserts in all the front cylinder base studs and the 2 front rear cylinder studs, basicly I did which ever ones I could drill out without pulling the motor. I slid an old picture between the crank top and under the case lip and put lots of white grease on the photo as well as in the stud hole and cleaned the shavings often. Those time-serts are the best thing since apple pie.
Club Member
Joined: Apr 2011
Posts: 5,827
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From: SE Louisiana
When I installed the helicoil I slid a piece of plastic cut from a grip package in there, also balled up a small piece of newspaper and dropped it in the hole, then used a vacuum, cupping a small hose in my hand in the end of the vacuum hose, to suck the shavings out of the hole as needed, Used a pick to get the paper out after tapping, Also used blue painters tape on the case around the rod,
At least I know how to keep all shavings out , now if I could just get the inserts in straight.
At least I know how to keep all shavings out , now if I could just get the inserts in straight.