bucket Posted February 4, 2009 Report Share Posted February 4, 2009 I just bought a 510 wagon with a L20B, for some reason the coolant pressure is way too high. I took out the thermostat to see if that was sticking open but it still runs with high pressure? The upper hose is rock hard and the relief valve on the radiator cap keeps blowing. What gives? I suspect there is a blow head gasket, are they related or is there a bigger problem that needs addressing? Pics to follow.:D -Bucket Quote Link to comment
ggzilla Posted February 4, 2009 Report Share Posted February 4, 2009 Yes, the two things that can add: - bad radiator cap - blown head gasket Quote Link to comment
hang_510 Posted February 4, 2009 Report Share Posted February 4, 2009 bad radiator? with the rad cap off(& thermostat out), does it seem like it trying to pressurize the system? you can see the pressure form the leaky HG in the radiator. when my HG went, this was how i determined it. it got to around 80psi :eek: at least everything else was solid :lol: Quote Link to comment
datzenmike Posted February 4, 2009 Report Share Posted February 4, 2009 Temporarily run with the rad cap loose, the air will leak out. Almost for sure it's a h/g. A compression test may show this but maybe not as it has to be a small leak at best right now. Run it cold with the cap off and watch for bubbles; they'll smell of gas. Quote Link to comment
hang_510 Posted February 4, 2009 Report Share Posted February 4, 2009 A compression test may show this but maybe not as it has to be a small leak at best right now. my HG failure was only at 2 coolant spots (rotted from sitting for 10yrs ... maybe :lol: ) the combustion chambers were nice and clean too. the comp check & leak down(had rad cap on :rolleyes: ) was normal :cursing: overheated and had to drive the 60mi home with the cap loose. Quote Link to comment
datsunaholic Posted February 4, 2009 Report Share Posted February 4, 2009 I was using compressed air to hold the valves in place while changing stem seals. After a couple minutes (had the air cranked up to 100PSI) the radiator cap relief valve lifted and it started gurgling out the expansion tank. Not a good sign, because it's letting pressure from the combustion chambers into the cooling system. One strange symptom of this is an engine that never warms up- I've had 3 engines with blown head gaskets that did that (ran just fine otherwise). Quote Link to comment
bucket Posted February 4, 2009 Author Report Share Posted February 4, 2009 well im petty sure its is the head gasket and im studying up so this weekend i can dig in. the only thing that still got me scratchin my head is the oil is still very dark so no water has gotten in. but the exsust is steam . good right. if there was milkshake would that mead my block may be cracked? Quote Link to comment
datsunaholic Posted February 4, 2009 Report Share Posted February 4, 2009 The lack of water in the oil just means the rings are holding, for now, and it's not leaking much when not running. You can get milky oil with just a blown gasket. Seen it many times. You can also get a badly blown gasket and no oil contamination at all... been there too (I had a steam jet coming out in front of #1 cylinder at the head gasket, and no oil contamination. Purely external leak there). Quote Link to comment
ggzilla Posted February 5, 2009 Report Share Posted February 5, 2009 Yes, I too have seen lots of engines with blown head gasket, but no water leaking into oil. It all depends on where the gasket blows. Sometimes it is just between two cylinders, not involving any water passages. Quote Link to comment
bucket Posted March 1, 2009 Author Report Share Posted March 1, 2009 ok head gaskets been changed and been driving daily for a few weeks. the last few dayss i noticed coolant is going fast. maby 1/2 gallon a day. but ive been noticed that the overflow dose its job a bit to well. then getting in after a quick stop i see a drip coming out of the hood way up near the driver window. under the hood i noticed the underside of the hood was wet and coolant has been all over. wether its related or not i also noticed theres a bit of moisture on the manifold gasket , like the felt is daker wet on the felt around the ports. what the hell is it now? Quote Link to comment
datzenmike Posted March 1, 2009 Report Share Posted March 1, 2009 (edited) Did you remove the manifolds when you changed the h/g? If yes, likely the manifold gasket is leaking where the water passages connect to the intake runners. Check bolt tightness. Edited March 1, 2009 by datzenmike Quote Link to comment
bucket Posted March 1, 2009 Author Report Share Posted March 1, 2009 i did have to retap one of thoe tricky inbetween hole on the head . but those bolts between the intake and exsust are a bitch Quote Link to comment
datzenmike Posted March 1, 2009 Report Share Posted March 1, 2009 Yes they are! Quote Link to comment
banzai510(hainz) Posted March 1, 2009 Report Share Posted March 1, 2009 yes the intakes have to be tight. Sometimes if the intake is loose it can suck water in the intake ports if it loose enough. Mybe run it without a T stat for a few days and see if still looseing water.If yes find out where. Mybe reinstall a new intake/exhaust gasket. if you run a L16 exhaust manifold your luck cause that is still ex to access the bolts. If a Later L20 type exhaust manifold then I feel your pain!!!!!!!U joint sockets Be careful not to X thread going back in!!!!!!! Quote Link to comment
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