zrex Posted March 13, 2020 Report Share Posted March 13, 2020 My 620 was puking coolant out the exhaust. Pulled the head expecting a blown head gasket, gasket looked good however. Cleaned the head and block surfaces and put in a new gasket. 30 seconds after start up clouds of coolant again. Pulled the head off again used a machinist straight edge to measure flatness of the head. A couple of things there’s a small crack between the valves on #3 and between cylinder numbers 2 and 3 I’m measuring a 6 thousandths valley. This is on my 78 so I still need to smog every 2 years. I have a real good A87 in the garage, will the A87 head without those steal liners work with those exhaust tubes? Another question is that crack a game over for the W58 head ? Not a large crack it’s a hair line but clearly visible.. thanks for any input 2 Quote Link to comment
wayno Posted March 13, 2020 Report Share Posted March 13, 2020 Can you post a photo of the crack? If it is coming out the exhaust at has to be a pretty big leak, when you rev it does coolant try to come out of the top radiator fill hole? 2 Quote Link to comment
datzenmike Posted March 13, 2020 Report Share Posted March 13, 2020 If it was burning coolant and you changed the gasket it could take over 20 min of running to clear all the water out of the exhaust pipe. Certainly I would have confirmed that it is using coolant before taking it apart again. All engines have some 'cracks' if you look close enough. You may have fixed it the first time. 2 Quote Link to comment
zrex Posted March 13, 2020 Author Report Share Posted March 13, 2020 Didn’t consider coolant in the exhaust pipe before I pulled the head off the 2nd time. 2 Quote Link to comment
wayno Posted March 13, 2020 Report Share Posted March 13, 2020 I didn't think of that either, it may have been coolant from the first blown headgasket, but you would have been loosing coolant if it still leaked the second head gasket, if the coolant level didn't drop then the second head gasket might have been alright. If the head is off I would get an opinion from someone at a machine shop that you trust that knows about cracks. 2 Quote Link to comment
Charlie69 Posted March 13, 2020 Report Share Posted March 13, 2020 Did you flush the cooling system including the heater after replacing the first head gasket? After the second? Did you flush the oil system in the block, head, and pan? 1 Quote Link to comment
gene knight Posted March 13, 2020 Report Share Posted March 13, 2020 (edited) i had that same problem on my L18 it was leaking between #2 and #3 above oil filter come to find out the machine shop milled the head wrong/ to much Edited March 13, 2020 by gene knight 1 Quote Link to comment
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