: The first head gasket failure - 1 out of around 90 or so

07-25-09, 09:39 PM
I guess nobody's really happy when a perfect record is broken. And I'm not, but as long as I can keep the rate of failure down to 1 in 100 or less, I'll be satisfied.

The job is still under warranty so it's back in my shop now. I wasn't going to post anything until I was sure it was a HG failure.

As per my warranty states, it has to be confirmed that it's a HG failing before I will do any warranty work. So, the owner took it to his oil change place and they did a test on it. Interesting how some shops work:

#1- they overlooked a blown heater core
#2- they said there was coolant on the #4 cyl. when it was PURE GASOLINE
#3- they did not do a compression test
#4- until the other day I never heard of anyone tasting spark plugs

The owner did not know where the coolant was going and the shop said the car was running rough because it was getting coolant in the #4 cylinder.

I began to pull plugs and noticed the #4 piston was washed clean. I figured it was coolant. I did a coolant leakdown test. The system held 18 psi and did not lose it. I did a leakdown test on all of the cylinders and pressurizing #4 was also pressurizing the cooling system. VERY LITTLE but any pressure is too much. The coolant had not gotten into the cylinder. The #4 intake valves were closed when I pulled the intake and there was liquid in the port. I stuck a Q-tip in the fluid and lit it with a match. Pure gasoline.

I removed the #4 injector and without 12 volts they should be shut. I pushed air through it and it was open. That explains the rough running. The injector was always shooting fuel, full blast. Failed injector.

I have the engine out and torn down now. The studs didn't fail, clamping force was still there. But there was a nick in the head right where the fire ring seals down.

I missed this nick. Looks almost like a factory defect- almost like a pore in the casting. There are no raised edges and it doesn't look fresh. The gasket is eaten around the fire ring from the gas, a small part of the gasket is washed away. I think gas seeped past this pore and ate the gasket and the exhaust gasses soon passed through to the coolant jacket.

The car is getting repaired once again for the customer, mostly at no charge. I might charge him for a replacement injector but this pore/nick is something I should not have missed. This head is garbage. Some might have it milled down but I have all kinds of spare heads.

It just ticks me off that his oil change shop could not figure out what was happening to the coolant, and that the #4 cylinder had to run on gas for so long because they can't tell the difference between gas and coolant. I'm pretty sure it would still be going strong had the gas not seeped into the pore.

Live and learn. Be more careful of head surfaces (even though I thought I was extremely picky).

I called this repair shop and explained what was going on. He said he tasted coolant on the spark plug. If he can taste coolant above the gasoline, I've got to hand it to him, his tastebuds are better than mine. Coolant never got into the cylinder at all.

07-26-09, 12:37 PM
jake.. i would'nt worry about it.. you still the best man for the job... my 2000 caddy you fixed is still running fine.. i do need that front motor mount though jake..lol... incase you cant figure out who this is..im the guy from nyc that came up a little while ago... my car never ran better... thanks jake...

07-26-09, 10:49 PM
I commend you for posting this... I will def. use studs if my heads go... and I just might bring it up to you... I dont let many people work on my car, but you are a real stand up guy.

07-27-09, 09:59 AM
Don't beat yourself up about it Jake. I will be getting my '98 Deville to you this fall from W.Va for repair. Keep it up.

07-27-09, 04:29 PM
Hi Jake -

I think a 99% success rate is really, really good. Also, I know the studs you installed in that car are still in great shape - just pull the head and install a new one! I can only imagine the nightmare if this repair had used timeserts and any of those had failed!

On another note, I've been researching coolant technology for the last couple of weeks. Have you considered using either Peak Global or Zerex G-05 coolant instead of a Dex-Cool equivalent? From my research, these seem to be the two best options to eliminate the risks associated with Dex-Cool . . .



07-27-09, 05:21 PM
Jake, I have never seen a person that takes as much pride in their work or is as careful as you. I would bet that is the first and last time you'll probably run into a nick like that anyways. My 98 now has 26K since you did it and still going very strong. I would recommend your shop to absolutely anyone, you are indeed a very stand up guy.

07-27-09, 06:07 PM
Nicks in the head sealing surface are an easy fix. Drill and tap a small, shallow hole at the start of the nick. Try not to go all the way through but it's no big deal if you do. Thread a piece of aluminum TIG welding rod with the appropriate thread, put some sealng compound on it, and screw it into the hole. You can adjust, adjustable threading dies for a good tight thread. Cut it off above the surface and drill and tap an overlapping hole farther down the knick. Repeat the process until the knick is filled. Peen the plugs a little bit with a small hammer to make sure they're good and tight. File the plugs off smooth and you're good to go. I've repaired cracks in diesel engine blocks and heads using this procedure with never a problem. On big, cast iron stuff I've used Morse taper reamers and pins for the repair.

07-28-09, 08:14 AM
Dkoz that would definitely be a good option for anyone who didn't have a bunch of spare heads- I ran into a few cracked blocks so the heads are still sitting on a skid ready and waiting.

I thank all of you for the kind words. Postman 2000, I will email you soon about that mount. I heard back from Hogg on where the mount broke that I built. This is an easy fix to my design. I will contact you soon.

I'll never achieve 100% again but I'd like to keep the success rate above 98% for sure.

08-06-09, 12:44 PM
Not to hijack this thread Jake :)

But are you still working on publishing a list of "reputable" shops who might use your kits in the New England area....When the boys Caddy comes off the road this Fall I'd love to make a preemptive strike and just get it done...

Mark :worship:


08-06-09, 11:18 PM
I've got my left head off waiting for the stud kit and head gasket.

What constitutes a nick in the head?

I've been real careful scraping the old head gasket off, but I'm afraid I may have already nicked my head.

Palmer, AK

08-07-09, 08:13 AM
It's actually because of global warming... so don't beat yourself up about it.


08-09-09, 10:29 PM
i have read about a "ridge" on the block? if you can mill the heads, than any raised edge/lip would be gone. is there a ridge on the iron cylinder in the block?

08-10-09, 08:41 AM
N* uses cast in sleeves (if memory serves).
The ridge in the bore is what I presume you are talking about, N* blocks and other components have pretty tight tolerances. It isn't like an old small block chevy.
If you can feel it, you pretty much toss whatever and start over with a new part.
Some things can be done, but not by much.

08-10-09, 09:53 AM
I think he's talking about something like a cylinder O-ring seal/ridge, not an upper bore "ring wear ridge". No such seal ridge, and you don't mill the block or heads for normal top overhaul. Maybe a .002" or .003" head cleanup cut, but that's it. The head gasket itself does have a standard stainless steel seal ring around the bore hole, but that's true of just about any head gasket.

Mill the heads enough to raise the compression ratio a quarter point or so, engine fuel ping increases and the knock sensor retards timing. You can't adjust static timing, so you're back to square 1. TANSTAAFL in a Northstar without completely separate engine management computer installation.

08-13-09, 07:09 PM
Jake (and all) - did you consider this?: Maybe the excess gasoline in the bore reduced the combustion chamber volume enough to increase the combustion chamber pressure dramatically? Not enough to hydrolock, but enough to find a slightly weak area to escape through?

08-20-09, 11:20 PM
I'll never achieve 100% again but I'd like to keep the success rate above 98% for sure.
Hmm. Last year my daughter brought me home a report card with straight A's except for 1 B grade. She was very nervous and upset about it promising it would not happen again. Next report card she had 2 B's and the rest A's. This time she wasn't as nervous or upset. Last report card of the year she had A's, a B and a freigin' C grade. She tells me "C's aren't so bad" and I'm thinking where the hell is the little girl that was so upset about bringing a single B?. Jake, don't get 2 B's...............................:suspense:

08-25-09, 09:37 PM
Destroyer, I don't let things slide. I made a mistake in not seeing that nick / gouge in the head. While I am constantly looking for ways to make the whole process more efficient, if it sacrafices quality I won't even think about it. I still tripple check bolt torque in each engine and I always will. There are some things you just cannot speed up and engine assembly is one of them. You can't afford to make any mistakes on an internal combustion engine and unfortunately I did.

I got "A"s in school too for a very long time until they decided to stick me in art class in high school, without my concent. You can lead a horse to water but you can't make it drink. You can make Jake fix a Cadillac but you can't make him draw one. Art was never my thing. Shop class on the other hand, well, that was fun.

Destroyer, I probably got an "F" in art class.

08-29-09, 12:48 PM
Jake, I need a set of those studs for my '96 Seville. Can I buy a set from you?

08-29-09, 05:13 PM
Certainly. We have a shipment going out Monday and Tuesday. Check out the website and click "add to cart", through paypal you can use your VISA or Mastercard.


08-30-09, 04:24 PM
Sorry for my ignorance, Jake, whats the website address? Also, does the motor have to be dropped to do this or can it be done in the vehicle?

08-30-09, 08:03 PM
The engine either has to be lowered or pulled out the top (not too bad pulling them out the top on the pre-98 Sevilles).


You will find it from there.

08-30-09, 08:03 PM
No apologies necessary JoeMugg :) :thumbsup:

09-02-09, 12:10 PM
... are you still working on publishing a list of "reputable" shops who might use your kits in the New England area ...

Jake, are you working on this New England list or can you refer me to someone in the NY / CT / MA / RI are who you feel is qualified to install one of your stud kits?

Many thanks!

2001 Deville DHS / 102K miles / HG repair on the horizon :(

09-02-09, 06:13 PM
Someone recently posted the name of a place in Boston and was quite happy with the service.

09-07-09, 07:58 AM
Sorry for the late reply, no not at the moment. Should have something soon.