canbaufo

Edit to subject!: I am now aware that there ARE NO COOLANT PASSAGES in the LT1 intake manifold. So now this is about whether or not I have a bad head gasket.

Most pertinent info first, possibly helpful background info next.

Pertinent info:

At cold start up (first proper one in 1.5 years due to finally fixing a miss caused by flooding) the engine smoked white from the valve cover breather, oil filler cap and tail pipes. I shut the engine off and looked things over for a few minutes and restarted it, no more smoking all the way through full operating temp and minutes longer (does not overheat or run oddly, runs great). There are no external leaks or ticking noises that I am able to detect. If the car sits for a few minutes after being shut off I can pull the oil filler cap and find evidence of what I believe to be antifreeze unfortunately.... at the very least harmless condensation, but it smells like antifreeze darnit.

You can restart the car multiple times while hot or after sitting "semi-hot" like 15 minutes and there is no white smoke. Only happens when cold started, this may be due to accumulation of antifreeze and/or condensation in cap / breather / underside of valvecovers after sitting for hours or days (no PCV system, just a breather.. which exacerbates this).

Initially I thought it was fine and assumed it had only smoked like that due to excessive condensation coming out of the engine since it hadn't been run properly or well into full operating temperature for such a very long time. Especially since it stopped smoking once warmed up.

But then I came back two weeks later and started the car again to observe the same thing happening (but i think to a slightly lesser degree). Now I wonder if I have a head gasket leak (or warped head) that shows up when the engine is cold, but perhaps goes away once it is warmed up due to metal expansion. Maybe I just need to take it for a 30 minute drive and burn 1.5 years of crap out of it.

But if this is a worst case scenario and I may have a very small / slow leak from a head gasket (antifreeze and oil levels not changing notably ..yet) would it be considerable to use a high quality stop leak type of product in the antifreeze? I once spoke with a skilled engine builder that doesn't like to use sealant on cylinder head bolts because he prefers to focus on accurate torque values. IIRC he said he prefers to run stop leak in the radiator to seal that area, as he feels accurate torque values are more important on cylinder head bolts. Remembering this conversation (and the fact that I'm preparing the car for sale) I wondered if it might be appropriate for this possible situation too? I would disclose the information to whoever buys the car. Thoughts on these options and recommendations for a top notch product if it exists (Blue Devil)?? Concerned that it may be of risk to the waterpump and possibly more.

After doing some research I have edited this post some and realize since this engine hasn't truly gone for a real drive for a very long time, I suppose it is possible that it is harmless condensation burning off. I did run the engine up to operating temperature in the driveway, probably for 6 - 10 minutes each of those two times, but no load and no drive. But since the moisture in the oil filler cap and tube seems so much like antifreeze that is what really concerns me. I can see that plain old condensation would be normal there, especially without a PCV system, but it sure did smell like antifreeze. Could even that be harmless???? It is hard for me to imagine so.

The most pertinent info is above, but some background info may help form some opinions

Backround info:

I had a miss that a mechanic was unable to diagnose (Absolute Horsepower LLC). The problem was a failed Aeromotive AFPR that leaked fuel through the diaphragm and into the intake manifold through the vacuum line / port. At idle and no load he ran somewhere between 1/2 tank and a full tank of fuel through the engine in this state ("troubleshooting run time") while it flooded badly enough to make the rear 4 cylinders not fire (the front four could fire, but very rich of course). It flooded the crankcase with probably two quarts of gasoline.... I found this after taking the car away from him and changing the oil.. eek! I Ieplaced the AFPR with a quality Borg Warner unit and it runs great now...in the driveway anyway. Exercising caution before putting the engine under load.

The smoking wasn't as bad the second time I ran it as the first time. I am concerned that the tremendous amounts of fuel the rear cylinders were subjected to (and heat on the front side of the engine vs little heat being generated on the backside) warped something or washed out head gaskets. It ran rich on the front 4 cylinders vs being flooded to the point of not firing on the rear 4. Hopefully he didn't run it real hot for very long for a lot of that run time.

Here's the post that explains the whole dilemma I've been through but there's no need to read through it unless you're just bored:

https://www.camaroz28.com/forums/lt1...htmare-886492/

Any and all advice / personal experiences greatly appreciated as always! Thanks

canbaufo

I'm nervous that I may only have a minor head gasket leak but that I could "fully blow" the gasket(s) if I go about diagnosing it the wrong way. For example, if I pressure test the cooling system I could induce a dramatic failure. Maybe I could use another method and if a very minor leak is confirmed use a sealant like Blue Devil (or maybe there's something better).

I've thought of some common sense things I can try. Next time I start the car I'll take the oil filter cap off and watch the valve cover hole while someone else starts the car. If smoke IMMEDIATELY comes out in a puffing fashion then obviously that's a failed gasket. If it doesn't smoke until some heat builds up and only "steams out" instead of puffing, I suppose it's possible that is only condensation and residual fuel burning out. I've also seen info about testers that check for the presence of fuel in the antifreeze.

Key worrisome things :

- Oil is slightly over filled while radiator is slightly low
- Smoke from valve covers and exhaust verified on two cold starts (but only at cold start)
- Upon inspecting the oil filter at last oil change it looked a little milkshakey, but the oil itself and dipstick were not.
- Engine was flooded dramatically by the Aeromotive AFPR leaking into the intake while careless mechanic continued to run the engine
- Inside of oil filler cap smells like antifreeze after the car sits and cools down.

To those knowledgeable about the way the head gaskets interface everything, please elaborate on what is likely and unlikely and advise accordingly. Please take no offense at me suggesting potentially using a head gasket sealant in the radiator. I think most will say do not do it or that even if it seals while running in the driveway that doesn't mean it could seal under boost / load. But I have to ask in case there's a situation that it's appropriate or has worked, depending on where and how the gasket is leaking.

Before I start the car again I will fill the radiator and drain some oil. Of course, if radiator level goes down again and oil level goes up again, that would appear to be a dead giveaway. I just hate to run it to find out, if running it is going to cause a full on gasket blow out.

Some positive things that may mean it's NOT a blown gasket:

- Starts up and runs great, doesn't overheat running up to 10 minutes in the driveway.
- No audible leak
- Cannot detect smoke once you shut the car off from the cold start and restart it. Each of the two times I've started it since replacing the bad AFPR and changing oil it smoked for a minute or so and I shut it off out of panic. Then restarted minutes later and no smoking. So if I were to continually run it upon cold start up (without shutting it off at all) I don't know if it would stop smoking or not.

Sorry for the length of the post, trying to provide a thorough description of what I'm observing. If anyone can help or advise (or correct any misunderstanding I may be demonstrating) I would really appreciate it. Thank you!

Gtpguy

Bad head gasket(s).

Staying cool while idling in the driveway, but go out and drive it over 50Mph and it will overheat fast. My ssei acted similar. Idled at a normal temp in the driveway, soon as it drove it pegged.

Seriously consider finding a good condition LT1 and swap, head gaskets are just about the biggest PITA, a motor swap can be done in hours.

1995_LR

Headgasket. Don't bother thinking about anything else because you have described a headgasket in near perfect detail. Your next step is to find which side. You can pull the plugs and look for the clean one or run a compression test and look for the one (or two) that's low. To say that doing a headgasket is harder than an engine swap is pretty far out there. Easily done and back on the road in a slow Saturday with lunch, smoke, and beer breaks peppered throughout. If you were dedicated and organized, you could do a head gasket in 4-5 hours. The problem is that you have a lot of "while I am in here" sorts of things you can get into. Pull intake - 20 minutes. Pull exh manifold on bad side - 20 minutes. Drain block - 5 minutes. Pull off whatever accessories are attached to the head: 30 minutes (lollygagging). Remove rockers and pushrods - 5 minutes. Remove head bolts - 5 minutes. Remove head. 5 minutes. Remove HG, scrape and clean - 20 minutes. Remove residue from head (including intake mani side), scrape and clean: 20 minutes. Install HG, head and torque-to-spec: 20 minutes. Install exhaust: 10 minutes. Install pushrods and rockers and set lash: 20 minutes. Clean opposite head of gasket residue: 10 minutes. Clean intake manifold of gasket residue: 15 minutes. Set intake gaskets down, RTV china wall, set intake and torque to spec: 20 minutes. Install whatever accessories were removed from the face of the head: 15 minutes. 4 hours if you are on-task at a decent pace. (Wait 24 hours for RTV to set-up and cure)

Notice how I have not mentioned anything about a stop-leak. Just don't do it - even if you're selling it. It makes everything a total ****show to work on down the road. Sell it 'as is' or spend the sub $100 to put in a new HG yourself.

canbaufo

1995_LR, thank you so much! That is the kind of detailed response I've been waiting for. I guess the main other thing to be prepared for is that a head may be warped or cracked, but I kind of doubt it since it was never driven under load. Hopefully worst case it would just need to be milled. I know my block was decked to "0", would that matter? I'm going to guess most would feel it's silly to only replace one head gasket while in there? Although it would save a significant amount of work. I've never done anything quite that detailed but figure I could, in about 30 - 40 hours. Yes, that's right, I'm just that methodical and that's all there is to it. Seems most shops would charge 15 hours labor to do it. I hate throwing more money at this car that I've wanted to sell for about 2 years now, but after all I've been through (man, it's a LOT) it seems a little silly to give up over a $100 set of gaskets and maybe even paying someone. I'm already out about $3,000 on various things since I decided to sell the car:

- Someone backed into my front bumper (poor old man, I paid for it)
- Someone rear ended me (poor couple traveling, I paid for it)
- Supercharger completely grenaded (I rebuilt it)
- Fiasco with Absolute Horsepower LLC, as they had the car captive at their place for nearly 6 months, while they flooded my engine during troubleshooting chasing spark issues as the problem was the wonderful Aeromotive AFPR leaking fuel into the intake, now apparently causing a leaky head gasket (they never figured out the AFPR issue, I had to do it with some help in here).
- Down time has caused other inadvertent expenses (travel to car, taxes, insurance)

What's another $2,000 or so...this car's worth a fortune right???!!?!?

You said I described a bad head gasket in perfect detail. Curious, why does the smoking stop once it's shut off and restarted and/or warmed up? Perhaps it's able to seal once warm due to expansion, or maybe the smoke is disguised somewhat once warmed up? Definitely a clean oil filler tube when warm, but after cool down the condensation shows.

1995_LR

Don't bother replacing the other HG if it doesn't need it. Either they are good or they aren't. They sell HG's per-piece, not per-pair, too. Whichever side it is, have the head checked at a machine shop. Pressure tested and flattened. Last time I did it, they charged me like $30. You said your block was zero decked... Was that after the supercharger was installed or before? Was the zero deck taken into consideration when the engine was built for boost? Changing the deck height will change your compression ratio - in your case, it increased it. Increasing the CR with a FI engine may have pushed it beyond the range of what is safe and what the normal HG's can handle.

I have no idea what a shop would charge to do this work as I've always done them myself. If you think its worth it to have a shop do it - then have at it.

I seriously doubt the leaking FPR would blow a HG. Never heard of that being a symptom. My guess is that your spark (?) issues were the HG from the get-go since water doesn't like to ignite.

canbaufo

I probably shouldn't have mentioned the zero deck just to avoid confusion. It is a built 355 engine and the compression ratio is 9.5:1, even taking the zero deck into consideration. There is no spark issue and never was (other than not being able to fire properly in the rear four cylinders due to being flooded by the failed Aeromotive regulator). It now runs absolutely perfectly in the driveway at no load all the way up to full operating temperature and it holds it. Throttle response is crisp as it ever was. I have read some posts of people claiming a failed AFPR caused a head gasket to fail, whether it is true or not I don't know of course. My initial fear was that my rings were washed out by all of the excess fuel getting into the crankcase. I do not detect any blue smoke whatsoever when revving the engine in the driveway, wether cold or hot. Only white smoke or Steam, whichever it really is and only at cold start.

The best case scenario here would be that I am wrong and that I simply have a huge buildup of moisture in the engine that needs to be burned off by a real drive. The problem is the inside of the oil filler cap smells like antifreeze to me. I guess it is possible that the oil level is overfilled simply because there is still some gasoline in the crankcase and that it has nothing to do with antifreeze. I also suppose it is possible that when they filled my radiator up after doing an optispark swap they simply neglected to top off the overfill tank. I doubt it though, my suspicion is that the overflow tank was empty because the radiator has emptied into the oil causing the radiator level to drop and thus purging the overflow tank.

Keep in mind that my engine (crankcase) was flooded with probably at least two quarts of gasoline. Running it in that state while making 20 psi fuel pressure and having the regulator leak tremendous amounts of fuel into the vacuum line that goes to the port on the back side of the manifold between cylinder #'s 6 - 8 seems to be a potential head gasket killer to me. But that is mere speculation. Perhaps there was a lot of detonation going on, even at no load. The shop admitted to me that they ran nearly a tank of fuel through my engine while trying to "troublshoot". They told me they detected a raw gas smell too. The moment I heard this I thought to myself, "I wonder how badly my Crankcase is overfilled with gasoline and oil?" Of course when I went over there to check it out that was exactly the case. It was a key thing it made me decide to take the car away from them, because it was such poor judgment to keep running the engine the way they did. You know, there are other ways to diagnose an issue then running the engine into the ground while you scratch your head?!?!? I put a vacuum pump on the Aeromotive regulator and that is how I ultimately figured out it was the issue, no engine running required!

To clarify, I have changed the oil twice since I got it back from them. It is showing overfilled on the dipstick by nearly a hash mark, but I think that's how it was the moment I filled it up, before I even fired the engine with the good fuel pressure regulator on it for the first time. Maybe antifreeze can leak into the oil even before the engine is fired up, I don't have the expertise to know.

Injuneer

Put enough liquid fuel in a cylinder, and crank the starter, there is a very good chance you will blow a head gasket. You can't compress a liquid. Blown head gasket is better than hydro locking it and damaging something else.

1995_LR

Bajeezus. Yeah, as Injuneer said, you're lucky it was not hydrolocked. Yes, antifreeze can leak into the crankcase with the engine off if the gasket is totally blown out. Not much, but it can. If the gasket was blown out that badly though, you'd have milkshake oil and oil in your overflow.

canbaufo

Thanks for the replies guys.

Assuming it IS a blown head gasket, what is the reason the white smoking from the oil filler cap and exhaust stops once the engine is shut off and restarted, or warmed up (whichever of the two is causing the white smoke to subside, not sure on cause and effect going from memory of two times that I ran the engine in the last month)??? Perhaps metal expansion minimizing the leak to an undetectable level?

I have limited time to work on the car which is across town, so I need to confirm a bad head gasket the quickest / easiest or most accurate way possible. Any advice there?

I'm guessing everyone is in agreement that a liquid gasket maker like Blue Devil is inappropriate regardless of the type or severity of the leak (again assuming a bad head gasket)?

1995_LR

Other tests you can do: https://www.2carpros.com/articles/he...ket-blown-test

Pullngz

"Starts up and runs great, doesn't overheat running up to 10 minutes in the driveway"

Take it for a drive, a blown head gasket is a blown head gasket. Get it up to operating temp and see what is does under load. Sound like you are trying to convince yourself that it is "just blown a little" A blown gasket is in fact blown, bad, needs replaced. In a short drive you're going to have your answer. There is no mystery oil that is going to repair a blown head gasket. Stop guessing, and take it for a ride and see if it's blown. Do a compression test or a leak down test.

canbaufo

Thanks for the feedback everyone (and the links). It will be a week or so before I can make time to go across town to the car, so I'm learning what I can in the meantime.

No one has commented on what the reason may be that it doesn't smoke once restarted or warmed up. Is it likely metal expansion temporarily sealing or minimizing the leak? Or maybe engine hest disguising it by burning it more effectively?

I have reservations about taking it for a drive because it could blow more severely and damage something else. I'm pretty convinced there's a head gasket issue. Perhaps the inside of the oil filler cap will tell me more next time I see it.

I used to know a guy that builds engines many years ago, lives out of state and we've lost touch. He helped design and build mine and he's brilliant (did Trig formulas on Excel spreadsheets to design custom cams). I'm paraphrasing and trying to remember a conversation from like 15 years ago, but he said something about not liking to use sealant on head bolts in order to get a more accurate torque reading. He said something to the effect of "and if they'd leak there I'd just run stop leak in the radiator and no big deal". He had high standards, so I thought if something like that worked in that situation it might work for a slow enough or small enough head gasket leak, that's the only reason I even ask if something like Blue Devil could be considered.

I may be misquoting him or maybe just misunderstood.

Injuneer

Leaking head bolts are not the same as a leaking head gasket. Coolant pressure is 18 PSI. Combustion chamber pressure is way higher when the fuel ignites and burns. Can not compare a head bolt leak to a head gasket leak.

GM actually recommends stop-leak tablets for the LT1 with a fresh coolant change, but it isn’t to stop head gasket leaks. It's to stop low pressure leaks like the bolts. But I am not aware of anyone that actually uses the tablets. They use head bolt sealant. Stop-leak is not going to seal a head gasket leak. If the mechanic was afraid using head bolt sealant was going to affect the bolt torquing, all he had to do was install studs, using the sealant.

This thread is going exactly the same way the last one went, with the four misfiring rear cylinders. In the very first response, post #2, I suggested you check the fuel pressure. But you gave a jumbled answer indicating the mechanic had determined the pressure was low and bypassed the inline pump, and it was OK. You insisted on following the diagnosis and advice of your mechanic, and trying to develop theories explaining why the people who were trying to help you were wrong.

This went on for 20 more extremely lengthy posts, where you (or your mechanic) kept coming up with new theories about the problem, pretty much rejecting the advice you were given. Finally I told you that you had to get the car back and get your hands dirty. At that point I just stopped helping. Only then did the problem with the Aeromotive fuel pressure regulator come.to light. I see the same frustration developing above.

1995_LR

Sealant on the head-bolts of an LT1 is mandatory, and the builder encouraged the use of stop-leak. I am starting to see where your problems began.

Your builder was a f-ing moron.