Paulmac201
Member
- Joined
- Apr 23, 2023
Thanks for the information. Much appreciated. I will talk to them on Monday morning.
Head Gasket Failure
- Thread starter Paulmac201
- Start date
TIMINATOR
Well-Known Member
- Joined
- Jan 26, 2020
Bearing clearance looks tight or line hone is bad, or both. Was the oiling system modified/ ported? What brand and weight oil was in there?
How about a pic of the deck and cylinder head close up showing the machining finish on both. The old rotary broach finish is waaaay too rough and wavy to hold any appreciable boost.
The surface finish should look almost like chrome. Only a CBN tooled head and deck mill will do the job correctly.
When I bought my Turbo T it kicked out both center cylinders headgaskets at 10 lbs. within 10 miles on a freshly rebuilt (apparently with old school carbide tooled) equipment.
The head and block finishes were both rough enough to use as a fingernail file.
The pic is of a BBC head with gasket failure. Look at the difference of the first .002" cut. The old finish was done with CBN diamonds that apparently were old and needed replacement.
Decent quality CBNs cost over $100.00 each.
TIMINATOR
How about a pic of the deck and cylinder head close up showing the machining finish on both. The old rotary broach finish is waaaay too rough and wavy to hold any appreciable boost.
The surface finish should look almost like chrome. Only a CBN tooled head and deck mill will do the job correctly.
When I bought my Turbo T it kicked out both center cylinders headgaskets at 10 lbs. within 10 miles on a freshly rebuilt (apparently with old school carbide tooled) equipment.
The head and block finishes were both rough enough to use as a fingernail file.
The pic is of a BBC head with gasket failure. Look at the difference of the first .002" cut. The old finish was done with CBN diamonds that apparently were old and needed replacement.
Decent quality CBNs cost over $100.00 each.
TIMINATOR
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626gn
Well-Known Member
- Joined
- Feb 15, 2009
As much of a pain it might be at this point, I would consider getting your car back and go to plan B. Your current builder may have the years but if they don't know TR's, that should have been your cue to keep looking. He may very well be a great in his area of specialty but he is literally learning about TR's on yours. A competent shop should know how to machine a block and heads without you having to tell them?
There is a Mid West section on this board. Maybe look for someone local to you who might be able to help or recommend a shop that knows these cars. These are all just suggestions but in the long run, probably better than the path you are currently on. Hope you get everything sorted out. Good luck.
TIMINATOR
Well-Known Member
- Joined
- Jan 26, 2020
A high end shop may not know about the intracasies of Turbo Buick clearances and oiling mods and such, but should have the proper equipment and know how to BHJ deck a block and mill heads.
Get the line hone and oiling mods done before BHJ decking the block. Both will change main roundness and actual deck height.
Also make sure whomever line hones the block has and uses a short arbor, and is not going to use a V-8 arbor with blank stones, as the overhang of a long arbor will bell the end bearing bores oversize.
That can be a big deal as the #1 and #4 mains will be a larger size and that will affect the clearances and crush of those bearings. V-8 and I-6 arbors are about 4 feet long without the drive shaft. Small V-6s such as ours and 4 cyl. arbors are about a foot or so shorter. Arbors are several thousand dollars each, so if a shop doesn't normally do these motors, he won't have one. Line boring will work fine, but again most shops don't have one of those unless they commonly do billet cap installs, and that too is a rarity since aftermarket blocks are quite common anymore.
Normal race shop main sizing is within three ten thousandths. Yup, less than a third of a thousandth! Factory specs are two or three times that.
TIMINATOR
Get the line hone and oiling mods done before BHJ decking the block. Both will change main roundness and actual deck height.
Also make sure whomever line hones the block has and uses a short arbor, and is not going to use a V-8 arbor with blank stones, as the overhang of a long arbor will bell the end bearing bores oversize.
That can be a big deal as the #1 and #4 mains will be a larger size and that will affect the clearances and crush of those bearings. V-8 and I-6 arbors are about 4 feet long without the drive shaft. Small V-6s such as ours and 4 cyl. arbors are about a foot or so shorter. Arbors are several thousand dollars each, so if a shop doesn't normally do these motors, he won't have one. Line boring will work fine, but again most shops don't have one of those unless they commonly do billet cap installs, and that too is a rarity since aftermarket blocks are quite common anymore.
Normal race shop main sizing is within three ten thousandths. Yup, less than a third of a thousandth! Factory specs are two or three times that.
TIMINATOR
Pronto
Believe nothing you hear and half of what you see.
- Joined
- Dec 9, 2002
Sorry that was for Paulmac201. If he had ARP studs he might not have had full clamping. The nut can bottom out on the stud without fully clamping on several positions.
TIMINATOR
Well-Known Member
- Joined
- Jan 26, 2020
On every engine I build, I retap every hole in the block and heads to make sure they are clean and full depth. I have seen many head bolt holes not threaded deep enough for the stock bolts that were factory installed. With stock engines those may run fine for years before causing gasket leakage.
Certain years of BBChevies and 455 Olds engines are notorious for bottoming bolts/studs.
Besides, depending on whether the heads have been milled, how much, and how often, and has the block been decked? Or zero decked even more?
There are major differences between a HP machinist, a job shop machinist, a HP engine builder, and an assembler.
This is assembly 101, check everything!
Assume nothing!
The more engines you "build", the more factory f-ups you will encounter.
One of the main advantages to studs is to use the entire depth of threads in the block. That's why studs are longer than bolts. Holes have to be deeper than the bolts so that they won't bottom out before fully clamping if the surfaces are later machined, or bolts are supplied by different manufacturers of slightly different lengths.
Studs are longer to use the full depth of threads at the bottom of the hole for greater strength. It is the builders duty to check for problems with the hole depth/thread engagement, and overall grip length before cleaning and assembleing the engine.
You should not only own a set of taps, but bottoming taps, and take the time to install the bolts or studs to the bottom of their respective holes and measure before attempting cleaning and assembly.
This scenario only partially explains why professionals command the prices they do for their work.
TIMINATOR
Certain years of BBChevies and 455 Olds engines are notorious for bottoming bolts/studs.
Besides, depending on whether the heads have been milled, how much, and how often, and has the block been decked? Or zero decked even more?
There are major differences between a HP machinist, a job shop machinist, a HP engine builder, and an assembler.
This is assembly 101, check everything!
Assume nothing!
The more engines you "build", the more factory f-ups you will encounter.
One of the main advantages to studs is to use the entire depth of threads in the block. That's why studs are longer than bolts. Holes have to be deeper than the bolts so that they won't bottom out before fully clamping if the surfaces are later machined, or bolts are supplied by different manufacturers of slightly different lengths.
Studs are longer to use the full depth of threads at the bottom of the hole for greater strength. It is the builders duty to check for problems with the hole depth/thread engagement, and overall grip length before cleaning and assembleing the engine.
You should not only own a set of taps, but bottoming taps, and take the time to install the bolts or studs to the bottom of their respective holes and measure before attempting cleaning and assembly.
This scenario only partially explains why professionals command the prices they do for their work.
TIMINATOR
Paulmac201
Member
- Joined
- Apr 23, 2023
Thanks for the response. I spoke to the engine builder this morning and he is well aware of the need to finish the heads and block when using a composite Cometic head gasket. They are confident that the Felpro was not the correct head gasket in the first place and are standing behind their work. These guys have 50+ years experience and the owner is a former drag race guy at a local dragstrip that closed up years ago. He has a great reputation in the industry and is a helluva nice guy.
I would like to find a mechanic with extensive experience with turbos and more specifically Buick Grand Nationals. I want to take the car there after this repair. The engine is completely rebuilt with the items that I purchased from GN1 Performance. I have them listed in my signature.
I appreciate the input from everyone on this site since you guys know these cars and I don't. I just want the car to be driven easy and taken to car shows and around town at the end of the day. I am not looking to take it to a dragstrip. I always wanted a Buick GN and I am finally at the point in my life where I can afford one. I just need to get it on the road. Thanks again.
I would like to find a mechanic with extensive experience with turbos and more specifically Buick Grand Nationals. I want to take the car there after this repair. The engine is completely rebuilt with the items that I purchased from GN1 Performance. I have them listed in my signature.
I appreciate the input from everyone on this site since you guys know these cars and I don't. I just want the car to be driven easy and taken to car shows and around town at the end of the day. I am not looking to take it to a dragstrip. I always wanted a Buick GN and I am finally at the point in my life where I can afford one. I just need to get it on the road. Thanks again.
Probably not the fault of the gasket. Lots of people running 9441's don't have problems.
The tune-up probably tells more about what happened then anything.
Lots of people in here going on about the surface finish.... Not saying that is not "the right way" to do it. But there's thousands of engines that get a razor blade rebuild and run fine. Mine included. at 21PSI of boost with 9441's and ARP head bolts. I look at the 9441 as the "fuse".
Main piece of advice I have is to use the Permatex copper spray on the head gaskets. Works great at sealing the imperfections.
If the head is warped that's another story. But a flat stone should be able to show you where the issues lie.
How's the wiring harness? did you read plugs at any point? Also if you have a scan master or whatever that's great. But having a modified turbo car without an AFR gauge is reckless. Protect your investment. The first time I get on the car each time I drive it I stare at the wideband gauge like its going out of style.
The tune-up probably tells more about what happened then anything.
Lots of people in here going on about the surface finish.... Not saying that is not "the right way" to do it. But there's thousands of engines that get a razor blade rebuild and run fine. Mine included. at 21PSI of boost with 9441's and ARP head bolts. I look at the 9441 as the "fuse".
Main piece of advice I have is to use the Permatex copper spray on the head gaskets. Works great at sealing the imperfections.
If the head is warped that's another story. But a flat stone should be able to show you where the issues lie.
How's the wiring harness? did you read plugs at any point? Also if you have a scan master or whatever that's great. But having a modified turbo car without an AFR gauge is reckless. Protect your investment. The first time I get on the car each time I drive it I stare at the wideband gauge like its going out of style.
626gn
Well-Known Member
- Joined
- Feb 15, 2009
A gasket like the 9441 would be more forgiving in terms of surface finish. For a MLS gasket like Cometics, not so much.
- Joined
- Jun 9, 2013
Well when mine blew at 26psi and no detonation we called up FELPRO.My heads are studded with ARP hardware and the rep said do not use the 9441’s for anything over stock boost as they cannot handle that kind of cylinder pressure maybe the older ones where of better quality but the newer ones aren’t ..They were giving up for a while on every cylinder and all that material went through the motor it was a disaster.He also said at the time the cars are getting old and there’s no money in it for FELPRO to make a gasket for these cars to withstand high boost.His words.
- Joined
- Jul 28, 2020
I’ve been following this thread, & have seen great info. That being said, the OP has not posted any info on WHY the head gaskets blew. NONE!
I used the Fel-Pro’s to 25ish P.S.I. & had 0 issues. Going to Cometic’s will take away your fuse IMO. Now instead of the head gaskets blowing, you’ll be putting all that pressure somewhere else. Cometic’s don’t give near as easy.
I feel OP has no idea why the head gaskets blew. That’s a BIG problem. No idea what turbo is on the car, no idea whether head bolt or studs were used, no idea what the tune(if any) is, If OP has a rebuilt motor with no way to get data(Scanmaster, Powerlogger, etc). This will be a repeat scenario.
Info has to be the first step. Or OP will be paying A LOT more to get the car fixed. Was there knock? If so how much? What was the AFR, TPS, etc. All these things are important.
I used the Fel-Pro’s to 25ish P.S.I. & had 0 issues. Going to Cometic’s will take away your fuse IMO. Now instead of the head gaskets blowing, you’ll be putting all that pressure somewhere else. Cometic’s don’t give near as easy.
I feel OP has no idea why the head gaskets blew. That’s a BIG problem. No idea what turbo is on the car, no idea whether head bolt or studs were used, no idea what the tune(if any) is, If OP has a rebuilt motor with no way to get data(Scanmaster, Powerlogger, etc). This will be a repeat scenario.
Info has to be the first step. Or OP will be paying A LOT more to get the car fixed. Was there knock? If so how much? What was the AFR, TPS, etc. All these things are important.
Paulmac201
Member
- Joined
- Apr 23, 2023
I am going to find out. One of the reasons that I posted this thread is to find a turbo mechanic. So far I have gotten no help there. None.
- Joined
- Jul 28, 2020
I completely understand your issue. The Turbo Farm is in IL. Lots of knowledge/help there. As for IN not sure who’s around there.
Unfortunately it’s a bit late now to find out why they blew now. You have no idea other than “mid boost”. I know I’m coming across as a dick, but you paid a lot of cashito to have a motor built, but chose not to use a known Buick builder(not necessarily a bad thing).
I get that ya just want a driver. IMO you’re going to need to dig a bit. Get to know your car. That’ll help A LOT!! Know your turbo, cam, was the chip set-up for your exact build, what converter, who built it, what your engine is doing when you’re driving(Scanmaster/SM G) at the least. This will help you when ya find a mechanic, & for when posting issues like this.
These motors are VERY finicky. They can take abuse to a great extent, but everything needs to be spot on. They’re not cheap to build, rebuild, or operate for that matter….LOL.
Just trying to help. I know you’re new to Buicks & are trying to learn. IMO the best way to do that is know your car, what you’ve done to it, & read up on here. You may find quickly it’s more financially feasible to do a lot of the work yourself, if you’re up to that.
TireFryer
The New Kid
- Joined
- Dec 21, 2001
I've tickled 30 before. I run the car around every day at about 27. Been perfect since 2020 when I put the car together.... I wouldn't use them again after reading this thread but whatever I got 4 years ago seems to hold up...
- Joined
- Jun 9, 2013
Motor still had to be completely torn down was full of material.I bent a rod on 6 damaged a lifter bore so new lifters rod and valvesprings,new front cover and oil pump assembly.Diamond Pistons and Roller Cam had no damage and the BMS crank that was shot peened and nitride coated polished out.All new bearings obviously machined block and heads accordingly for Cometics.All in all the fuse cost me $7500 in parts and machine work.That was with me pulling it and putting it back in.
- Joined
- Jun 9, 2013
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