90 ZR1: Oh crud, did I break it?
 

Happy Thanksgiving everyone. The wife and I decided to take the ZR1 to the family turkey extravaganza about 15 miles up the road. It ran great all the way there and half-way back. At the half way point, things got ugly.

All of a sudden there was a loss of power and the engine was running rough. Definitely not hitting on all cylinders. Pulled up at a stop light and it didn't really want to stay running. Without giving it little throttle bursts, it would have died.

There was no "drama" leading up to this. I hadn't been hot-rodding. There wasn't any bang or other indication. Gauges remained normal and no indications on the cluster.

At the next light I saw that there was smoke coming out the back when I gave a little gas.

We limped home and into the garage and I shut it down. It smells to me like there's unburned fuel in the exhaust. We unloaded the leftovers (mmmm... turkey....) and then came out and lifted the hood. No signs of external trauma. Nothing leaking, seeping or oozing. Oil is still full (and clean).

Started her up again and it continued to run like crud. White smoke from the exhaust.

Just under 28k miles. No mods save for a B&B exhaust and K&N filter from previous owner.

I'm trying to reassure the wife that the car we got 3 weeks ago will be alright again. I know the injectors are notorious on these cars, but maybe it's spark.

Any recommendations on where to start? Maybe this looks familiar to somebody.

Re: 90 ZR1: Oh crud, did I break it?
 

Pull plugs and see which if any look like they've been steam cleaned. It may not be a head gasket. If it looks like either #4 or #3 cylinder, it can be the IH to head interface. Coolant port runs very close to the primary runners of those cylinders. Very little material separating the port and coolant. Over time it can corrupt the gasket and burrow its way under it especially during high vacuum situations like idle or decel.

Re: 90 ZR1: Oh crud, did I break it?
 

Blown head gasket? Ew.

The radiator over flow bottle has water in it.... not much. It's at the "cold" line. Engine's been off for about an hour. Garage is about 45 deg.

What else should I look for to confirm/deny it? And I guess next question... how hard is it to replace (find?) an LT5 head gasket? <ducking>

Re: 90 ZR1: Oh crud, did I break it?
 

Shaving cream milky sustance on the oil dipstick. About $89.00 per side on Ebay

Re: 90 ZR1: Oh crud, did I break it?
 

Thanks Xfire751. I guess next I will need to figure out how to pull the plugs on this beast. They look well buried, and I have very little experience with this car. Dumb question: what's the "IH" in "IH to head interface"? Lucky for me... there's a shop manual in the back!

Re: 90 ZR1: Oh crud, did I break it?
 

Man, you guys are QUICK on this board. Not used to that! :)

Goldcylon, the oil dipstick looked nice and normal to me and I checked within 2 minutes of pulling in the garage.

I may wait till daylight for more digging since lighting in my garage pretty sell stinks.

Re: 90 ZR1: Oh crud, did I break it?
 

IH ="s Injector Housing

Re: 90 ZR1: Oh crud, did I break it?
 

Duh. Injector Housing. Got my service manual out and I'm going to study. Thanks gents for the input. Anything else you think I ought to know, hip me to it. I'm grateful for the knowledge here.:notworthy

Re: 90 ZR1: Oh crud, did I break it?
 

Do you smell gas and does the smoke come out of only one exhaust pipe? If so could be a blown fuel injector. If it is you will quickly burn out the cat on the side with the bad injector. Very same thing happened to ZZZZZR-1 David.

Re: 90 ZR1: Oh crud, did I break it?
 

Hey Jagdpanzer. Matter of fact, I don't smell gas. It smells sweet. Which leads me to think Dynomite was onto something from the git-go with the water. Understood on the cat though. Just went through that on a buddy's Acura.

Just looking through the service manual to get to the IH and related gaskets. Sweet Jeebuz what a PITA! Looks like it's about the same amount of labor to get to it or the head gasket.

What I didn't want = project car. Too bad I'm already hooked on the thing!

Re: 90 ZR1: Oh crud, did I break it?
 

do an oil change and see what the oil looks like. the good/bad is you're closeish to corry henderson if anything did go south on you http://www.hendersonperformance.com/

Re: 90 ZR1: Oh crud, did I break it?
 

hopefully the previous owner didn't use dexcool in the car

Re: 90 ZR1: Oh crud, did I break it?
 

You might want to also check the MAP sensor hose. If it comes off, the car will run like crap.

http://i13.photobucket.com/albums/a2...oprearview.jpg

Re: 90 ZR1: Oh crud, did I break it?
 

What color is your coolant? Green or Orange? If it isn't green, you better replace both of the head gaskets. Dexcool destroys the gaskets in the LT5. Hopefully the previous owner wasn't foolish enough to put in Dexcool. You can save yourself a lot of grief by taking the beast to Corey Henderson and having him replace the head gaskets. While the engine is apart seriously consider porting and doing a 368. You won't regret it.

Re: 90 ZR1: Oh crud, did I break it?
 

Also check MAP if filled with oil.

Pete

Re: 90 ZR1: Oh crud, did I break it?
 

Good grief, this board is crazy helpful. If nothing else, I've learned this ZR1 crowd is way cool. That may sound odd but coming from the groups I've known before, I don't take it for granted.

The coolant is the standard green glycol stuff. I think it's safe in that respect. I'll look at that MAP sensor when I get some daylight.

I've read up on Corey and in fact have had a couple guys I know locally mention him & his shop. Nothing but good stuff. If it turns into a project, he's certainly going to get a call from me. First I'm going to go local. We do have a shop in town that's qualified on LT5 and recommended by a buddy of mine so I will give him a call in the morning as well.

I'm actually still astonished I'm getting any input at all, much less helpful input.

Re: 90 ZR1: Oh crud, did I break it?
 

Oh forgot.
Welcome to the jungle.
Happy Thanksgiving.

Pete

PS
Head gaskets are not very common unless overheated,run lean or something silly.

Can i get some pictures of your Firehawk?

Re: 90 ZR1: Oh crud, did I break it?
 

the only shop that I know of that does lt5 work in texas is corey, what's the name of this shop? not saying your buddy is wrong, but I just don't want to see you take the car to a shop that's going to do more harm then good.

Re: 90 ZR1: Oh crud, did I break it?
 

Yeah... I'm obviously more than a little concerned about the problem, seeing as how it's got me up at 3:30am.:dontknow:

Oddly enough, I don't have a bunch of pics of the 92 'hawk handy, but I'll pm you when I do, if you like.

Corvettes of Dallas has a service department and they're reportedly competent with the LT5. But don't worry... I've had enough experience with specialty cars that if they don't know what they're doing, the car will go elsewhere.

To be honest, I'm still on the fence about tearing into it myself. Thing is I still have the motor out of the GTO and I don't like the idea of having 2 cars in my garage pulled apart at once.

Re: 90 ZR1: Oh crud, did I break it?
 

I have a dealer near my place who was well known to be the place to take your car....i realized that was crap after they washed my engine and sprayed orange clean on it. if it was me, I'd drain the oil and go from there

Re: 90 ZR1: Oh crud, did I break it?
 

You might try looking up Jim Milstead known on here as "TheLurker"
He's from the Dallas area and knows the ZR-1 & LT5 as well as anybody and a great guy. I'm sure he can direct you to a competent local shop.

Re: 90 ZR1: Oh crud, did I break it?
 

Well, I wasn't able to get with "The Guy" at the shop today due to it being a holiday weekend and all. Same story at Corey Henderson's shop down in New Braunfels. So I'm going to have to try and exercise a little patience. The tech I talked to at Corvettes of Dallas (now Corvette World as of a couple weeks ago) says he's never broken down an LT5. He's never heard of one blowing a gasket like this. (Perfect... leave it to me).

He did mention that in order to get at the heads and pull the thing apart it could be necessary to pull the engine out of the car. That doesn't sound like any bit of fun. It sounds like a whole lot of money. Anybody have any words for me? I'm starting to get a little scared. A $10k engine rebuild is not within my realm of possibilities.

Re: 90 ZR1: Oh crud, did I break it?
 

Replacing the plugs are fairly easy but #8 can be a challenge.What works for me,a telescoping magnet,2 inch 3/8 extension and a 3/8 ratchet with a pivoting head.On the difficult plugs I drop the plug socket in the plug hole then the 2 inch extension loosen the plug.Fish everything out with the magnet.Im sure everybody has a different methed but this works for me.Other than the smoke Id have to say its a coil-injector problem.Id start the car and start pulling plug wires and listen for a no miss.If you work on your own car this LT5 is no different.Would like to see some pictures of that G.T.O. When I was a kid my Mom had a 67 4-speed.Wish I had it now.:(

Re: 90 ZR1: Oh crud, did I break it?
 

about the only thing i know of that will pop a head gasket on the LT5 is dexcool. did you check the map sensor?

Re: 90 ZR1: Oh crud, did I break it?
 

These pictures are a little misleading.If I didnt know this was a base car Id swear this was your Z with a chunk lopped out of it.

Re: 90 ZR1: Oh crud, did I break it?
 

I don't know if I missed it, but why do you think the headgasket is shot?

Re: 90 ZR1: Oh crud, did I break it?
 

I wouldn't let my mind go too crazy just yet.When one of the injectors died in my 8000 ZR-1 I had what sounded like a rod knock I thought I was dead in the water.The knock turned out to be the flywheel-cam chains making a racket with the dead cylinder.Getting to the IH looks like a big job,it is a pain in the a$$ if you've never done it but get tons of pictures as the thing comes apart and its a piece of cake.The most valuable asset is right here,a bunch of guys that have done it.

Re: 90 ZR1: Oh crud, did I break it?
 

I'm with Bob here..... I think we may be doing the chicken little thing regarding the head gasket.. Should save the worst for last. Worry when needed. BIG difference in replacing injector housing gaskets & replacing head gaskets.

EZ check for head gasket leak. Remove the radiator cap (while cool of course) watch for bubbles in the coolant.

Injector housing bolts do get loose. Loose bolts could let coolant leak into the intake runners, causing miss, white smoke & sweet smell in the exhaust, along with low coolant in the overflow reservoir. Could leak into cyl's 1,2,3 or 4. Plugs would be white. Remove plugs only when engine is cool to prevent seizing. Do a little sniff test on each cylinder while the plug is out.

Don't stress. Pretty unlikely to blow a head gasket just tooling down the road......especially on Thanksgiving with your wife in the car!

Re: 90 ZR1: Oh crud, did I break it?
 

If it is a blown head gasket or injector housing gasket coolant leak do not attampt to crank the engine over before removing all of the spark plugs or you run the risk of greater damage if a cylinder is full of coolant. With the spark plugs removed crank it over to make sure the cylinders are clear. Then install the plugs and start it up with the cooling system pressure cap removed. If the head gasket is blown bad enough to cause to the running problems you have discribed you should see air bubbeling out of the coolant pressure tank.

Re: 90 ZR1: Oh crud, did I break it?
 

I'll get out there and start looking. I'm not exactly sure *what* I'm looking for yet. :) I've never seen a "good" one, but based on some pretty good pics I saw earlier :notworthy: I've got to think I could probably at least rule it out. It doesn't appear to be dexcool related.

Based on advice so far and my experience with old cars (60's muscle)... steam in the exhaust & burning glycol usually says "blown gasket". Of course, I'm just not used to thinking about an IH gasket so my head doesn't automatically go there. Yet.

That's a very diplomatic way of saying "calm down, dude." :) OK. I will. All my tools are at my office so I'll either find some usable implements I've forgotten about in the garage, or I'll pick up my tools tomorrow and dig in. Thanks for the motivational words.

Re: 90 ZR1: Oh crud, did I break it?
 

I"ve got a Universal Block Tester Kit I bought to use on my old LT-1 after I thought I blew a head gasket. there is approx a half bottle left of the testing fluid. It has all the instructions on how to test (really simple) for a head gasket leaking, cracked block etc. A simple matter of watching the fluid turning form blue to yellow is a leak is present.

If you want the kit I"ll send it to you for nothing but I"d like to get the postage back. If your interested, drop me a PM...

Re: 90 ZR1: Oh crud, did I break it?
 

from page 2
http://i13.photobucket.com/albums/a2...oprearview.jpg

you may have to pull the plenum to check the bottom side of it but that's an easy job.

Re: 90 ZR1: Oh crud, did I break it?
 

Geezzz... you guys can scare the new guys half to death with this head gasket talk. While I agree that the stated symptoms may point in that direction there are other possible causes. There is a simple and quick way to check for a blown head gasket. Go down to your local Autozone or Kragen and rent a cooling system pressure tester. Hook it up, follow the directions (important) if it holds pressure you don't have a blown head gasket, if the pressure won't hold and there's no puddle of coolant under the car you have either a blown headgasket or a blown IH gasket. Once you've done that we'll talk.
H
:cheers:

Re: 90 ZR1: Oh crud, did I break it?
 

I had the same thing happen 4 years ago. It was two bad injectors and an intermitten problem. Like you at the time I didn't know squat about the car (of course all of that's changed now). Took it to corey Henderson. Took him no time to chase down and fix what was wrong. But again it was to bad injectors. Running great and in a split sec ran like it was gonna self distruct.

Re: 90 ZR1: Oh crud, did I break it?
 

I'm on board 110% with Hans here. Save yourself a lot of time and get the cooling system tester. I'll never troubleshoot a cooling system again without using one of these. I had a leak in BG this year, once I got home I replaced the water pump (I was positive it was the pump as I saw fluif dripping off a lower pump bolt) before testing the system. After I replaced the pump there was still a leak so I decided to get the tester. Found a leaking hose. It was brand new set of Samco's and the hose going to the upper radiator had a small slit in it. I used the original clamps (spring type) and think they caused the problem. Don't know how the fluid got down on the pump bolt (if it did). There was a puddle of fluid right under the hose on the frame now. Samco replaced the hose and I used their clamps this time. Problem solved. But...now I have a water pump that may or may not be bad because I didn't test the system.

Hope that helps a little. The tester will absolutely tell you if you have a coolant leak. If you do this, pull the plugs first.

GL

Re: 90 ZR1: Oh crud, did I break it?
 

I am just curious if the car ran the same with the power key on as it did with it off. I had some secondary injectors go bad and the car ran rough with the key on, but ran OK with it off.

Ron

Re: 90 ZR1: Oh crud, did I break it?
 

I emailed you GTO but have not heard back from you.

Jim

Re: 90 ZR1: Oh crud, did I break it?
 

Hello there Jimbo :wave:

Re: 90 ZR1: Oh crud, did I break it?
 

OK, Update.... first of all, thank you for all the follow-ups and it's not that I've been ignoring you, but I got nasty sick on Friday and was down for most of the weekend. I dragged my sniffling self to work this morning just 'cause I didn't really have a choice. Now I'm feeling better so it's time to get the ZR1 feeling better!

NOW... for the excitement... This morning I came downstairs after getting ready for work and the wife says "it smells like gasoline down here". Being stuffed up still, I took her word for it. Until I got to the back hall and sure enough that was gasoline I smelled. I opened the garage door and it was really strong. Looked around under the car and found no puddles. Had to go to work.

Came home tonight & I managed to get all the plugs out except for 8. I'll go back and search for all the tips on how to get at 8, but what was GM thinking there?! :icon_scra

I compared all the plugs and they appear original (almost 28k miles on the car). #5 looks very fouled.

I bumped the starter a few times and watched for water to burble out one of the cylinders. When it hit #5, a geyser shot from the engine to the garage wall... on the far side of a 3 car garage! And it was gasoline.

I made another revolution with the starter and got the same result with slightly less gasoline bursting out. I got little "poofs" out of the others.

So now I'm thinking it's probably NOT water in there, but unburned fuel making its way out the exhaust valves and burning/evaporating off the inside of the hot exhaust, and that was the smoke I was seeing. Wouldn't that say "bad injector" to you? In which case, isn't that a big relief vs. it being a head gasket?

Whadya think?

Re: 90 ZR1: Oh crud, did I break it?
 

Appears you have found the problem.
Time to pull the plenum and replace the injectors