lespaul166

So I知 absolutely dumbfounded. I知 like 90% certain I have a blown coolant seal in my 86 GXL. Add coolant light comes on after 30ish minutes of driving, big blubbing bubbles when cars run hot with the cap removed, no coolant on the ground. The crazy thing is I stuck a pressure tester at about 13psi onto my coolant system on Saturday morning. I checked it Monday morning and the level hadn稚 dropped at all. Drove it 30 minutes home today and the light snapped on briefly as I accelerated and went out.

the crazy thing is there is absolutely NO smoke or coolant smell from my exhaust. For it to be burning that much coolant there would have to be SOMETHING. The car starts great, runs great. When I tried to start it this morning to pull it out it seemed to be missing a lot for a short second but then I revvd it and it started running fine again.

I just want to make sure I知 doing the right thing before pulling this engine, and not dropping $3000 in parts alone (my god these things are expensive) to rebuild my donor motor, only to have the light snap on as I知 taking it on a break in run.

edit: just went and checked my car, almost 3 hours after getting back and the coolant still hot, pressure under cap. Overflow is filled to the brim.

j9fd3s

iTrader: (3)

coolant seals can do different things depending on the random way it fails. my friend has a car that has something wrong with the coolant seal, and its intermittent, most of the time its totally fine, but sometimes it does what your car does.

i've seen some that hardly show symptoms at all, they will start on one rotor, and the coolant light will come on just for a second. and then some are big smoke shows

the inexpensive way to build these engines is to tear it down, measure everything, and then order the stuff that is actually bad.

WondrousBread

FWIW after tearing mine apart (for compression loss) I had a blown seal on the front iron and section of the groove rusted away to nothing on the rear.

No overheating, no coolant loss, no bubbles. No symptoms of the coolant seal being bad at all actually other than what you mentioned with the stumbling on cold-starts. If I hadn't lost compression (seemingly unrelated) I probably would've continued driving and never known until symptoms appeared.

doug910

My car is experiencing pretty much identical symptoms to yours, OP. My engine runs and drives great - it has great power, revs freely, idles fine, no smoke out of the exhaust nor any sweet smelling exhaust. It does stumble on cold starts a little bit though. The real issues occur after about 20-30 minutes of driving and my coolant buzzer comes on like yours, and the overflow bottle is filled all the way up. No symptoms in the exhaust make sense because I can pour all the coolant from the overflow back into the car and it goes back to the correct level in the cooling system. When I was bleeding the cooling system last weekend, I had some serious bubbles coming out of the funnel once the thermostat opened. It seems like the bubbles are over-pressurizing the cooling system and forcing the coolant out to the overflow. Maybe depending on how/where the coolant seals failed combined with the high pressures from the combustion gases, exhaust gases leak out but coolant doesn't leak in. When left overnight, perhaps a little bit of coolant seeps into the engine and causes the momentary hard starts while the engine clears out the coolant.

If you haven't done so already OP, make sure to change out your rad cap with a new OEM cap. I picked mine up for $20 from a Mazda dealership (sure, it's expensive for a rad cap, but money well spent imo to diagnose an engine). A faulty rad cap that doesn't hold proper pressure will let coolant escape into the overflow under normal operating temps. Aggressive bubbling kinda makes the diagnosis pretty pessimistic, but I guess a rad cap that doesn't hold pressure will also lower the boiling point of coolant and thus, could cause boiling. Nonetheless, good luck man. I'm going to tear the engine out soon myself and start saving my nickels.

Rotary Alkymist

n/a