rigel
03-31-2015, 09:47 AM
so, finally pulled the cylinder head (with intake manifold, separated later) on my 87 a20a1, and I was glad I went ahead and bought a spare carb from the JY because it gave me practice in disassembling it.
I had suspected a leaking head gasket because of rough running with lots of sweet smelling whitish smoke, but now I wonder if that was right. I has a slight loss of compression in cylinder 3 too, which supported the head gasket idea, and it had clearly been tunning rich for a while before, based on the condition of the plugs, they were hella sooty and maybe a bit oil fouled. other potential explanations could have been problems at the valve seats or seals I guess, but I thought (based on zero previous experience) that this was coolant smoke.
well, when I got the head off there was an ass ton of carbon, but no obvious problem in the head gasket. I lifted it off and (like the EGR valve gasket, same problem) it just disintegrated on me. I did note a misplaced intake manifold gasket on cyl 3 though, but it seemed to seal, just would have been thin in places.
gaskets that werent oil soaked or didn't fall apart on handling were brittle as hell, so I suppose they could have had hairline cracks?
stop leak had been used at least once because it was everywhere in the cooling system.
lord knows when the last maintenance had been done on this thing. and it still drips a little bit of oil (even after draining) and atf.
there is so much accumulated grime on the back side of the engine, good god.
its gonna rain for the next few days so I'm going to focus on cleaning up the head and valvetrain. then I will probably rebuild the oil and water pumps and try and scrape off some of this carbon before reassembling.
soooo, questions
what is a good scraping tool for all this gasket residue? I've used shards from broken CDs to remove crap from other metal surfaces without marring clear coat, so I'm thinking a polycarbonate ice scraper, given the extent of the crustiness here. the valve cleanup I have a nice procedure from YouTube, so I think I'm good there. I just want to be really careful about sealing surfaces.
also, I probably don't have the extra time for this project but I wonder how much extra work it would be to get down into the bottom end without an engine hoist? is that even possible? even the bad cylinder was producing 120ish psi on dry compression test but I suspect that might change significantly once I get rid of some of these carbon deposits.
basically I'm hoping that cleaning it up, replacing all the gaskets I can get my hands on, redoing the timing and adjusting the carb will at least get it back into running order enough that I can make a further determination about the tranny.
talking it out like this, I really have no idea why I'm going to all this trouble. "learning experience" I guess.
I had suspected a leaking head gasket because of rough running with lots of sweet smelling whitish smoke, but now I wonder if that was right. I has a slight loss of compression in cylinder 3 too, which supported the head gasket idea, and it had clearly been tunning rich for a while before, based on the condition of the plugs, they were hella sooty and maybe a bit oil fouled. other potential explanations could have been problems at the valve seats or seals I guess, but I thought (based on zero previous experience) that this was coolant smoke.
well, when I got the head off there was an ass ton of carbon, but no obvious problem in the head gasket. I lifted it off and (like the EGR valve gasket, same problem) it just disintegrated on me. I did note a misplaced intake manifold gasket on cyl 3 though, but it seemed to seal, just would have been thin in places.
gaskets that werent oil soaked or didn't fall apart on handling were brittle as hell, so I suppose they could have had hairline cracks?
stop leak had been used at least once because it was everywhere in the cooling system.
lord knows when the last maintenance had been done on this thing. and it still drips a little bit of oil (even after draining) and atf.
there is so much accumulated grime on the back side of the engine, good god.
its gonna rain for the next few days so I'm going to focus on cleaning up the head and valvetrain. then I will probably rebuild the oil and water pumps and try and scrape off some of this carbon before reassembling.
soooo, questions
what is a good scraping tool for all this gasket residue? I've used shards from broken CDs to remove crap from other metal surfaces without marring clear coat, so I'm thinking a polycarbonate ice scraper, given the extent of the crustiness here. the valve cleanup I have a nice procedure from YouTube, so I think I'm good there. I just want to be really careful about sealing surfaces.
also, I probably don't have the extra time for this project but I wonder how much extra work it would be to get down into the bottom end without an engine hoist? is that even possible? even the bad cylinder was producing 120ish psi on dry compression test but I suspect that might change significantly once I get rid of some of these carbon deposits.
basically I'm hoping that cleaning it up, replacing all the gaskets I can get my hands on, redoing the timing and adjusting the carb will at least get it back into running order enough that I can make a further determination about the tranny.
talking it out like this, I really have no idea why I'm going to all this trouble. "learning experience" I guess.