93 300zx tt coolant on spark plugs?

[Kevrock529]

I believe I have a blown headgasket, but want to see what everyone thinks because it seems wierd to me. I have not had the car for 2 years, as I had a friend do alot of body work done and repainted on the side.

I got the car back and the next day the car over heated. By the way it has 183k miles on it. I have owned the car since 2004. I changed out the injectors to 600cc new style myself prior to getting the body work done and did the usual deletes like egr, coolant plenum delete.

When it overheated, I drove it 30 minutes looked at temp gauge and noticed it was reading 3/4, which it normally sat at the half mark. Stopped at a restaurant and it poured coolant in parking lot. Let it cool, then drove it home slowly and temp gauge seemed to stay in middle when I got home shut it down and the engine girgled. Like coolant was draining but nothing was leaking anywhere under the car.

Took it to a close mechanic and they said upper radiator hose was cracked and radiator nipple was rotted which I think i knew about so replaced radiator, and upper and lower hoses. They said they let it idle for 45 minutes and took it for a drive and was all good. Got car back. Drove it for a long ride that next day everything fine for approx 30 minutes then again noticed temp gauge all of a sudden was going over the half way point about 30 minutes in. Was about 10 minutes from mechanic and drove it right there. Left it running so they could see. They reved it a few times to see if temp would drop, in the case id a bad water pump but didnt. I looked at exhaust and no white smoke at all out exhaust. (I always think worst case scenario so research bad head gasket prior to taking it in the first time). I instantly thought thermstat and they suggested lets do thermastat, which I thought about doing with radiator but they said lets do this first then do thermastat after if this doesnt fix it. I agreed so now they did thermastat.

So i leave car and they wait for it to cool down to change the thermstat. I ubered home. I get a call they changed the thermastat and when to start the car it would not turn over they said it was hydrolocked with coolant. They said it has to be the head gasket. I got a huge pit in my stomach and asked them to work up a quote for monday.

When they replaced the radiator, they pressure tested the coolant system and said it was fine. I feel like I know this car very well. I dont want to pay to dig in and pay for them to get to the head gasket and then say piston or something more serious is going on. If its a bad head buying new heads or resurfacing the original ones I would be willing to do.

I just need someones advice here and if a head gasket would go bad like that? It seemed instant. The coolant didnt have oil in it when radiator was replaced. I got the oil changed right after the radiator replacement at a quicky oil shop and they didnt say anything about oil being foamy ( which i can see maybe they didnt notice but i checked the oil cap and dip stick at home when it did the over heat girgle prior to the radiator replacement).

Any advice is greatly appreciated. I know this is long but I wanted to try to explain everything in detail. I also want to make sure I am not missing something else that it could be.

They also said the thermastat in there looked newer, which i never changed it in the 14 yrs I owned it. I also have a knock sensor bypass on the sensor. But engine ran excellent on the last run no hesitation, turbos spooled perfectly.

[nissanfreak12]

Do a leak down test. That will give you actual answer if you are leaking from the head gasket. If you are unsure how to do it, find a competent shop that knows how. Do not tell them what you think may be an issue. If they ask, just let them know you want to see the health of the engine. Compression test can tell you the same, but can be skewed because battery gets weaker, engine gets colder, etc.

Did you pull the plug and actually see coolant? The shop?

Does your upper radiator hose have pressure when it is hot? With the new radiator, did you get a new cap? Is you fan clutch working properly?

If you havent replaced the thermostat, even if it does look newer, replace it. It is possible it could be sticking.

[Kevrock529]

Since they changed the thermastat and then saw the coolant on the plugs, I have not been back to shop uet. They were supposed to call me today and did not. I also have friends in town so did not call them back today.

I do not even know at this point which plugs they found the coolant on. I assume it has to be one side or the other and not both sides?

The car from what I understand is not running at all. The last I heard friday was they they were taking the plugs out to remove the coolant. I am going to ask them to do a leak down test then. What does that actually involve and test for?

Is the head gasket the only way coolant could be in the plugs?

All the information i have is from the shop and I have not gone there to confirm or check anything yet. For the radiator, I assume it comes with a new cap so i will have to ask? How could the old radiator cap cause a problem? I have read something about the cap too in these forums.

I also assume they left the new thermastat in there. Clutch fan I believe is working but will mention that also. My biggest concern now is the coolant on plugs and it being hydrolocked from that.