Gary Lewis Posted 15 hours ago Share Posted 15 hours ago Ok, so that cylinder has about 33% loss. Did you find out where it is losing it? (Did you tell us this and I've forgotten? ) When I run a leak-down test I figure out where the air is going, and with 33% loss you should be able to hear it for sure. If the loss is in the sump, meaning it is getting past the rings, then that's why the PCV valve is getting gunked up. And replacing the heads isn't going to fix that. Link to comment Share on other sites More sharing options...
viven44 Posted 14 hours ago Share Posted 14 hours ago (edited) How about a double check on the Rockers Arm bolt torque ? If they are overtightened or tightened when things were not perfectly TDC, one of the valves may be just a hair open ?? When adjusting the Rockers, (I think) it is imperative to use a leakdown tester to ensure things are 100% sealed before torquing the Rocker arms. But I'd be curious to know how the other cylinders are doing ? If all 8 are in that same range you may just be dealing with an engine high in miles, but if 1 or 2 cylinders are off, just double check the rocker arms on those before coming to conclusion. Edited 14 hours ago by viven44 Link to comment Share on other sites More sharing options...
viven44 Posted 14 hours ago Share Posted 14 hours ago 1 hour ago, Gary Lewis said: When I run a leak-down test I figure out where the air is going, and with 33% loss you should be able to hear it for sure. Any tips on how to listen and where ? If its intake valve, through the carb throttle valve ? If its exhaust, in the exhaust tail pipe? If its the sump, maybe through valve covers?? Link to comment Share on other sites More sharing options...
Gary Lewis Posted 13 hours ago Share Posted 13 hours ago 3 minutes ago, viven44 said: Any tips on how to listen and where ? If its intake valve, through the carb throttle valve ? If its exhaust, in the exhaust tail pipe? If its the sump, maybe through valve covers?? Rings: Stick one end of a hose into the dip stick tube and the other into your ear Exhaust valves: The end of the exhaust pipe Intake valves: The carb or throttle body inlet Head gasket or head/block crack: The spark plug hole for adjacent cylinders and look for bubbles in the radiator 1 Link to comment Share on other sites More sharing options...
ReneH Posted 13 hours ago Author Share Posted 13 hours ago I have heard and used a lighter to check if air is comeing through the exhaust or the throttle body. I've set the throttle to full open before. Nothing on both. For the dipstick tube, I haven't use a hose. But maybe the loss also was caused by a defective connector on my compressed air hose...I will do the test later this year. I best case, when I've got new heads... I know, that new heads won't fix this. But if I do the test, before changing the heads, I'm able to also change the rings in this step....this was my idea... Link to comment Share on other sites More sharing options...
Gary Lewis Posted 13 hours ago Share Posted 13 hours ago If the rings didn't seal to the cylinders you may not be able to get new ones to seal either without honing the cylinders. There has to be a texture to the cylinder walls to get the rings to seal. I wouldn't want to pull the heads w/o knowing if the rings haven't sealed 'cause I wouldn't want to go through all of that work and then learn I need to take it apart again. And the way to find out if the rings have sealed is to run a leak-down test on each cylinder. If you have something like 33% leakage on all of the cylinders then you may want to change out the heads w/o doing anything to the rings. But if one cylinder is worse you'll have to make a decision. Link to comment Share on other sites More sharing options...
ReneH Posted 8 hours ago Author Share Posted 8 hours ago (edited) As you may remember, I've let bore, hone and measure the cylinders when stroking the engine. I have a protocol...each cylinder has be bored and honed to one according piston. The engine builder has got the pistons together with the block. I've had a nice texture inside the cylinders and it's still there. I've made pictures with my stethoscope camera when I've changes the plugs last time... So if the rings aren't sealing, maybe the rings were bad...🤔 And as I've commented before, I lost air through the compressed air connector, so my measurement may be not the best... Edited 8 hours ago by ReneH Link to comment Share on other sites More sharing options...
Gary Lewis Posted 7 hours ago Share Posted 7 hours ago The rings might not have been compatible with the cylinder prep. I've seen that before and didn't get the rings to seal. Had to replace them with a different type, and those sealed. I'm just suggesting that you find out if there is a problem before you swap the heads as the time to fix a ring problem is when the heads are off. And yes, a leak can lower the reading. Maybe that will bring the 33% lose down. Link to comment Share on other sites More sharing options...
Recommended Posts