Bought a 300zx for a decent price.. found this behind the thermostat. can anyone identify what caused this?!

[aretwodetwo]

Stumped over the cause of this nasty goop gelatinous substance that was stuck behind the thermostat.. (pictures attached to the bottom of the post)

the story: bought a 1992 300zx with 98,000 miles for a pretty fair price, rebuilt transmission, two new turbos to replace the locked up turbo, and a super clean body, changed the oil with mobil1 full synthetic and the mobil 1 filter, the owner never put the turbos on because his wife got pregnant and never ended up with enough time to fix her up. I offered him a deal and swooped up the beast after getting to know a little about it. Its been sitting for 15 years (surprisingly engine is not ceased) and I pulled the engine over the weekend to do the timing belt, water pump, piston rings, head gasket, arp head studs, engine seal kit, radiator, hoses and silicone vacuum lines and put the new turbos, clutch assembly and transmission all mated together. An insufficient amount of coolant came out of the radiator when I drained the coolant... maybe about 2 quarts, but no chunks (yet) lol, no milky substance, just green coolant. oil is golden and no milky substance either. I pulled off the intake plenum when I got the engine on the stand and pulled off the front timing cover and then the coolant hard pipes next to the water pump, then came the thermostat which was kind of stuck on there but with minimal force came off and behind the thermostat was a nasty surprise... can you guys identify this? it looks to me just like expired coolant that's been sitting for 15 years behind a thermostat because I know water and oil do not mix and I did not find any pockets of oil in the mess, nor was it really oily.. it just was rusty and a coagulated gelatinous mixture.

Any advice on how, why, when, and where it came from is a big help and would be much appreciated!! the engine is being taken down to almost the bare block, can I flush this stuff out? I was thinking of flushing the block and cylinder heads separately, taking off the block drains and shoving a garden hose through the jackets, same stuff for the cylinder head, then taking Evapo-Rust which is a great product to dissolve rust without the harsh acids and leaving that in the coolant jackets over night then repeating that two or three times.

Thanks again in advance for all the help! anything is appreciated!

-Jonathan

[url]/http://imgur.com/a/4tIup
[img]http://imgur.com/a/4tIup

[lexcrob]

I've seen that before. Never quite that bad. Id maybe suspect it was some form of "stop leak".

Save yourself the trouble of trying to clean them trust me.

Drop it all off at the machine shop they use a big super duper heated pressure washer oven thing that will blast it cleaner than you ever can.

Normally the cost is like 20 bucks for block and heads.

Maybe have them check the heads and block for cracks/warping.
Also normally cheap.

[aretwodetwo]

I'll drop them off when I have time. Thanks for the info Lexcrob! Much appreciated

[aretwodetwo]

I called around to a few places in my area and they all want at least 70$ for the block and 50$ for each head! JUST for hot tanking. Isn't that a bit too much??

[rgregoryb]

Nope, you own a Z32, they think you like to spend all your money on it.

[lexcrob]

That is a bit high. If you have a large commercial truck service facility sometimes they have there own "hot tank". Might be able to ask.

Ask how much crack testing is also they may give a "package deal".

Id start the conversation with. I planning on maybe needing a bunch of things done. First I need to.....

Most of the time small machine shops will work with you. Although if they make most there money on small engines or industrial stuff ur number 2 to them.