Hold Me, R3V

[c0rbin9]

UPDATE: The later part of this thread is about my intermittent no start problem, which was the fusible link. As for the head gasket, it seems to be fine.

I'm worried that I cracked my M42's head/headgasket.

A few days ago I had completed a cooling system overhaul (complete flush, water pump, thermostat) and when I was bleeding the system the car got up to 3/4 on the temperature gauge, much hotter than normal. I also heard a loud crack when I went for a drive but I'm assuming this is unrelated.

Anyway, 3 days later, I've finally gotten the car bled and running okay. Temperature seems to be fine. I'm worried about the overheating incident though. Engine doesn't sound as smooth and the car maybe doesn't seem to pull as hard. Also my oil seems thinner than usual.

Kind of disappointed because I have a thing for the engine matching the chassis. How should I check for a cracked head?

[c0rbin9]

Actually I think I remember adding quite a bit of water while the car was hot, thinking the high temperature was just because of the correct thermostat... perhaps the loud crack I heard was the head going SPLIT from the temperature difference.

[ak-]

3/4ths is fine. Letting the needle go into the red is when you should start to worry.
Adding cold water to the res. while the engine is hot won't cause any problems.

TBH it's al probably in your head, but to rest easy do a compression check and a leakdown if you're still wondering if you have the time.

[Das Delfin]

my 325 doesn't get hotter than half, but what you were probably experiencing was the lack of a proper bleed. Air in the cooling system can cause a lot of issues

there is really only one t-stat you can get for these cars, an 80 degree C unit. Assuming you searched by part number found on realoem and ordered from fcpeuro or whatever

[george graves]

3/4ths is fine.

Do you really think so? I kindly disagree. A proper well running motor should never get to 3/4ths. Sure if might not cause damage, but it's a sign of something is up for sure. No?

[roguetoaster]

Unless it's blowing grey exhaust or getting oil/coolant mixing you will be fine. For the former, start the car from cold and look, then wait for it to warm up again. For the latter, look at the oil cap/dipstick for something that looks like rancid milkshake or check the coolant reservoir for oily film, especially on the cap.

Since it looks like this thread got moved to the M42 forum there are several things to address. There are several thermostat temps to pick from, stock is best. While 3/4 won't hurt the engine (you might get there with the A/C on in traffic on a hot day) it's not something you want to see regularly.

[ak-]

Do you really think so? I kindly disagree. A proper well running motor should never get to 3/4ths. Sure if might not cause damage, but it's a sign of something is up for sure. No?

Sorry, I meant it as in his engine is fine and undamaged if it reached that temperature as you said.
It is not optimal, efficient, nor normal being in that range though. Correct!

A proper well running motor will sit at and hover around half.

[roguetoaster]

A proper well running motor will sit at and hover around half.

There's also the question of gauge functionality, as I know when mine was acting up the gauge would flutter right around 3/4.

[c0rbin9]

Drove to work this morning, temperature was perfect the entire way, opened hood to check coolant level and it was overflowing out of the tank and onto the ground. I'm HOPING it's because I'm running almost 100% water (temporarily) or because the cap wasn't tightened all the way.

Otherwise it's hello MR2, cause I need a daily driver, and don't have time to swap a head for my first time.

[roguetoaster]

Your cap may be past it, or it may be (but isn't as the car is not overheating) exhaust gasses in the coolant system if you are certain that you tightened it. Now that water came out it's a safe bet that you'd need to bleed it again.

By the way, a head swap takes perhaps 4 hours the first time you do it.

[c0rbin9]

Bad news.

Drove home fine, overflowing issue was probably just loose cap.

However, now the car doesn't start. I thought it was my hot start issue resurfacing but I let it cool down and it still doesn't start. Just cranks quickly.

[roguetoaster]

Verify spark and fuel, go from there.

[c0rbin9]

Thanks Rogue.

Anyway - this morning I had the car towed back to my house on a flatbed. Of course, just as the driver leaves I try to start the car and it starts right up.

This car was abused by the previous owner, and now I'm suspecting something electrical since this is the second time that having it jiggling around on a flatbed magically makes it start, even when it wouldn't start after being completely cooled down.

Any ideas on where to start poking around for electrical faults? I've got a multimeter...

[roguetoaster]

Look at the connector on your fuel pump first.

Then check all of your grounds.

Beyond that, anything that looks like it has been messed with (read not put back together correctly) is suspect.

[c0rbin9]

Will do, thanks.