Actually when they are cleaned up I like them

 

Im a big basket weave fan on the c4. Ignore the troll. Let keep it on the subject.

 

Barchetta1, the car did not overheat, at least since I have owned it. It was leaking coolant and I decided to have the water pump
replaced BEFORE I overheated. The more I think about it I may or may not have head gasket issues but I don't think that is
what is causing my current problem. The car barely runs now, stumbles bad and barely pulled itself out of the garage. I have
not seen a simple leaking head gasket, without a radiator full of oil looking like a milkshake, cause a car to run like mine is.
My guess is the shop tested the compression and stopped looking for the ignition issue that is causing my problem.
I will do the compression test, both normal and wet like the Hagerty video ZWILDZR1 provided, and test the coolant like
Hot Rod Roy suggested.

 

You paid for a compression test. Id ask for the readings. Just for fun. Here will be the response "sorry we didnt keep them". I think you have an ignition problem as well. I dont know squat about the l98 ignition so I have nothing to offer. As mentioned though, there will be no nasty coolant and no milkshake oil if its a cyl to cyl leak. I dont know what tools you have but a very simple test would be coolant pressure. not sure about the l98 but lt1 plug holes are a bear to get to.. Since your car runs this bad its not just a little leak if it is a leak at all..What a bunch of slimeballs would be my guess.. jeeez.

 

generally, a head gasket to coolant blow out pressurizes the coolant system and the radiator cap lifts; you'll often see bubbling in the coolant.
a cylinder to cylinder head gasket blow out will be a loss of power; which at first my not even be noticeable, but it will get worse.
In either case, a compression test will tell all. Compression figures are hard to predict, but all cylinder should be within 10 to 15 per cent of each other.

In any case, retest the compression.

And, after the plug wires have been yanked on and pulled / pushed on and off, plan on replacing the plug wires. The conductors harden with heat and age and eventually fracture...so even if they look good on the outside, it ain't necessarily so on the inside..

Why would the engine go from running to hardly running so suddenly? If the compression is good, and the ignition is good (try the old laying a plug on the engine with a plug wire attached to it, crank the engine and hope to see a strong spark across the spark plug electrodes); then you probably have a fuel issue; test for fuel pressure; if low or non existent, then that's a problem.

One thing that could fail instantaneously is the diaphragm in the fuel pressure regulator; that would flood the intake with fuel and cause all sorts of driveability issues. If the fuel pressure comes up, but immediately drops off when the engine is shut off, suspect the regulator..

 

If its an aluminum head, its not unheard of for a valve seat to come adrift from the head and prevent the valve from closing. That is something that could fall into "it ran great yesterday" scenario.

 

This is precisely why Ive not changed out my spark plugs or wires.. I dont want to disturb them.. hahahah Im amazed they still work after 25 yrs.. although the lt1 came with platinum tips so they do well over time. I'll never find plug wires that have the cyl #'s stamped on them either which is nice. But yeah, I dont dare even release them from the plastic separators.. I just wash them clean of oil and gunk. The lt1 as I mentioned is a real back breaker to replace the rear plugs or it would be done by now.

I agree, this could be fuel too.. Id love to get my hands on this car with the right tools.. very fun diagnostics. If you dont own a nice stant coolant pressure tester and a fuel pressure gauge now would be a great time to own them. another one would be a scope.. I just ordered one for $125 which is a 50mhz/ 1g samples per second.. cant wait to get it.. with something like that you can check injectors and ignition to the nth degree. Part of the fun of owning an old sports car is understanding it and making sure everything is up to factory specs.. I'll also be able to check my egr... oh and a vacum gauge.. and pump.. with all these tools (about $300) you can do a lot of diagnostics.

I didnt see where mentioned any smoke.. so Im banking on ignition still.. cant wait to find out.

Assuming you prove this shop was in grave error Id make sure to yelp or something to warn others.. 95% of people would just say ok, I trust you and I want my car back when can it be done? Jerks. If Im wrong about this Im going to feel bad now.

 

Adrift? can you explain please? Oh the seat.. nevermind.. it can happen but unless this engine was really pushed I doubt it.

 

It will be a real shame if this isnt a head failure.. it would give him an excuse to do some upgrades.. wife approved too I bet... honey Im going to spend a lot of time on this.. id like to spend just a little more and make it really nice for "us". I know all the angles.

 

I doubt it too, but I have seen it happen in street cars made by manufacturers whose reputation is "reliability" driven by ordinary drivers in very ordinary ways....TAKE THAT Toyota and Nissan.

 

Overheating can do it.. valve meet seat.. valve and seat meet heat..valve and seat now one unit. Doubt it in this case though..

with no mention of smoke its either lean fuel, some sort of injector control failure (don't know how it works on l98) or ignition/ignition control. Which doesn't narrow it down much but probably right.I suppose a ginormous vacuum leak is another possibility.does the l98 use a map sensor? How does it meter air?

 

No smoke, no milky foam in the oil, problem came on suddenly, doesn't sound like a compression problem to me. I think your mechanic just wasn't interested in working on your car. A misfire on one cylinder will make it run rough but it should still idle and drive without too much problem. I had a blown injector fuse once. They don't run well on 4 cylinders, But it still would still start and run. That was easy to diagnose, the header on that side was cool enough to touch.

 

HOLY CRAP!! That's a lot of cash for a head job. A good head job, seals, guides valve job on a stock set of heads should not be more than $400, not including labor of removing and reinstalling. $3,500 is WAY TOO MUCH! Is he selling you new heads? I have an issue with your so called mechanic since he THINKS it might be head related. Wha? He didn't even bother to check that and is now just playing a guessing game at your expense. THAT IS NOT A GOOD MECHANIC! Like mentioned, do a leak down test and gas check to see if it is indeed head related. Save yourself a lot of cash or unless you just like to throw money away. If so, you can send me cash at...PM for account number.

 

I'm not that familiar with L98 intake manifolds, but it wouldn't be the first time to have a perfectly operating EGR valve with a carbon clogged EGR passage in the manifold; when the EGR valve was off, did your mechanic blow compressed air through the passages to ensure that they were open?

 

I'm not saying their quote is high or low, but it's a lot of work and depending on what they are having done to the heads and the labor that could very easily see $3500. I know you only paid 5k for it, but parts and labor hours do not change depending on what you purchase a car for. At one point that car was $35k so you could look at that way as well.

 

i liked the rims... just saying... real spokes,, them things are sweeeet. just need gold plated inards with black trim that would be the fajizzel fo shizzle

 

no but seriously.. them rims are cool man red inside with the chrome or white would really make that car pop


ps... there is no mild upgrade really, it's like a fish tank, sure you can buy a 50 gallon... but a year later you want the 150 gallon

so just buy the 150 gallon n be done with it...

 

I'm going with the theory that the guy who inspected it knew what he was doing and gave an honest evaluation. Since the coolant isn't going bazerk when its running then I would figure the head gaskets are blown between cylinders. Sure be nice to get the compression numbers they got. I'd remove the Spark Plugs they might lead You to what cylinders are bad. To do a leak down test You will need Compressed Air but not for a Compression test. If you have Compressed Air You can do a Ruff Leak down test with out a leak down tester. If You blow Air into a Spark Plug hole when its at Top Dead Center on the Compression stroke it will build pressure instantly. And if it doesn't You will detect the Air coming out the Intake ( Valve ) Exhaust (Valve) or the surrounding Spark Plug holes ( Gasket or Crack). If any of these happen well for sure the Heads are coming off. At this point You might consider having another set of heads rebuilt ahead of time and or a set of new replacement heads. Best case You find nothing wrong and install a new set of Spark Plugs and it runs again.

 

i am really wanting to buy new brodix heads, what would ya give me for the stock ones i take off? they should be fine and in pure stock condition, 120 k on the engine
it runs as is right now, runs damn well i might add. 90 ... shifting 4'th gear and got scared at about 120 on the back road

 

that convertible top sounded like it was coming off... so i let off the pedal going into the curves..

then again, maybe they arn't stock.... might of already been to liongerfelters before i owned it for all i know.. he is just a few miles away afterall..

91 l98 heads... is what it would bei have the exhaust manifolds also since i just bought hooker hears.. all for sale..