Project Lex

[Halon]

Small update. Did a quick compression test on the motor. Got 165-170-165-165-172-165. Albeit the motor was cold, but none the less I thought that was a pretty good initial sign. I'd like to do it again with the motor warm, but until I've checked over some more things I'd rather not get things hot yet.

[asshanson]

I didn't realize a hg issue would impact compression numbers, unless it was totally destroyed. Slightly warped might only leak at high boost pressures.
Regardless, 219 shouldn't be hot enough to break anything, but that's only where the temp sensor is, not necessarily at the hottest point. Good luck, hoping for the best for you!

[Halon]

Well a HG can fail in several different ways, and at several levels of severity. Depending on how it failed, a comp test may or may not show anything. I have a compression tester, so why not just spend 30 minutes to see if it showed anything. If anything, I think the results tell me there isn't a massive HG failure between two cylinders, or anything like that. And also tells me in general this motor still has healthy compression as those numbers I feel are excellent, so that's nice.

Next on my list are:
- Use brownman's coolant pressure tester to see if I can spot any coolant system leaks and fix any we find.
- Drain oil and coolant and see if it looks good or if there is any signs of mixing. If all looks good then just refill.
- Troubleshoot and fix radiator fans.
- Get wheels repaired, re-finished, and buy some new tires for all 4 wheels.
- Inspect under the car in general to see if I messed anything else up.

[Halon]

Grabbed brownmans tester over lunch and ran home and did a test. Pumped it up to about 14psi and not a single leak in sight, which was kinda promising actually.

I drained out the coolant to see if there was any signs of water/oil mixing. No signs at all, still looked good as new. So I think I'm going to skip draining the oil and looking at it because so far everything is looking good.

[Kracka]

Sounds great! I agree, unless there is foam on the underside of the oil cap or on the dipstick, I wouldn't bother with the oil. This really all does point to the radiator cap being worn/weak and just not holding the pressure needed to raise the boiling point. Most coolant boil/freeze charts assume the cooling system is pressurized to 15psi.

http://ls1tech.com/forums/attachments/general-maintenance-repairs/557884d1479621879-antifreeze-boiling-boil101bw.jpg

Note the column at 0 psi with a 33-44% mix; pretty much right where you boiled over. Fun fact, the C7 uses a 20psi cap (most are in the 12-16 range) which explains why it can run such hot temps without boil over issues.

[Halon]

The cap is a 0.9 bar cap. Maybe you are onto something, I will probably grab a new cap to be safe then. See if Stant makes one or something for this car. I see what you're getting at, but on the same note I don't think that the cap is holding in zero pressure, but perhaps it just opened up at some amount of pressure, thus relieving the system of pressure putting it down to 0 once it opened up, then the boiling started and kept going from there.

Thanks for the ideas!

[Kracka]

Stant, Gates, etc. all make a .9 bar (13 psi) cap for your car. I'm sure one of the local parts stores has to have one in stock for under $10!

[Speedfreak]

Yeah, just take a look at the dipstick, on the oil cap, and in the head through the oil cap opening (with a flashlight). If everything looks normal(no milky look). Appears all is well.

[Halon]

Yeah I see local places all have replacement caps. I like the kind with the little lever on them if I ever needed to manually relieve pressure (had that style on my DSM).

What interesting is 13psi seems to be the norm of the SC (also norm for a DSM). But a supra is the same cap but rated at 16psi (like an evo). Wondering if I should go with the higher pressure version.

[Kracka]

More Supra parts! Seems like we just had this conversation HAHA

For a high performance engine adding more cooling capacity is never a bad idea, but it will put more strain on the remaining stock cooling components.