Help! Unidentified coolant leak!

[Phanuel]

I recently did an engine out rebuild on my m20 and was doing the run in on a new cam today when I was done I noticed a large amount of coolant gushing underneath the car, off of the transmission pan. So it seems like its coming out of the back of the engine somewhere.

My first culprit was the hose coming off of the back of the cylinder head and the heater hoses, but there was no liquid on the head, block, or firewall. I can't find anything unconnected, loose, or evidence of a leak anywhere in the bay. I checked all my hoses in the engine bay and everything was tight, no leaks coming out of anything I could see, all dry. So I'm stumped and I need help diagnosing this issue from some e30 people who may be a bit more experienced than me.

Thanks

[e30davie]

About the only thing you can do differently is get one of those coolant pressure tester kits. little hand pump that sits on the radiator cap and you can pressurise the cooling system with the engine off so you can listen carefully and find the leak.

[roguetoaster]

Hoses can take a bit to seat if just on the edge of being tight and/or the hose or pipe it connects to are a bit dirty. Same can apply to the water pump. But if it's not leaking during idle when up to temperature I'd say you are unlikely to have an issue.

[ADEN]

Hoses can take a bit to seat if just on the edge of being tight and/or the hose or pipe it connects to are a bit dirty. Same can apply to the water pump. But if it's not leaking during idle when up to temperature I'd say you are unlikely to have an issue.

You reminded me of my m52tu leaking coolant out from the back of the engine and the exhuast area when both hot and under load, Leaking stops when idle or part load lol.

Just decreased the coolant temp to 87 using romrider and flashed the partial bin. Now 2 weeks with no leaks, When the budget allows head refresh is next.

[QUOTE=Phanuel;n10043406]I recently did an engine out rebuild on my m20 and was doing the run in on a new cam today when I was done I noticed a large amount of coolant gushing underneath the car, off of the transmission pan. So it seems like its coming out of the back of the engine somewhere.

My first culprit was the hose coming off of the back of the cylinder head and the heater hoses, but there was no liquid on the head, block, or firewall. I can't find anything unconnected, loose, or evidence of a leak anywhere in the bay. I checked all my hoses in the engine bay and everything was tight, no leaks coming out of anything I could see, all dry. So I'm stumped and I need help diagnosing this issue from some e30 people who may be a bit more experienced than me.

If the head turned out to be the problem try tightening the head bolts a little like 5 degrees and see if it stops before getting the heaf out again.

[Phanuel]

Thanks for the input fellas. At this point I'm fairly certain it's the heater core leaking as the drain leads down right over the transmission which is where the coolant was coming from. I'm gonna pull my console apart soon to confirm and repair