Bob Shell wrote: >On May 11, 2007, at 4:50 PM, Mark Roberts wrote: > >> Did they try using an exhaust gas (emissions tester) analyzer? A quart >> per month is not going to show up visibly or by smell so they need to >> find out *exactly* what's coming out of the tailpipe. > >I don't think these guys would know what an emissions tester is. >Since state inspections here don't require emission tests, I think >those gadgets are pretty rare. I'll ask around next week and see if >anyone has one.
This will tell you definitively if there's oil being burned. >> Next, see if you can find someone to do a leakdown test: Much more >> revealing than a compression test. > >Never heard of a leakdown test. I'll see if they know about that, too. A leakdown test is done with the engine shut off. You bring the piston to TDC, remove the spark plug and screw in the leakdown tester. It pumps in pressurized air and measures the rate at which it leaks out past the rings, and valves. It's unaffected by a number of variables that can affect a standard compression test. If leakage shows up, you can squirt a bit of oil into the cylinder, turn the crank a couple of times and re-test: If there's less leakage you've got bad rings; if it stays the same it's valves. Racing engine builders I know use leakdown testing pretty much universally now. Don't try to get a leakdown test done until after the exhaust gas test: I'll bet the emissions show oil being burned. If so, the leakdown text will narrow down where it's happening. If, as some have suggested, it's the valve guide seals, the oil burning will be happening mostly during deceleration, when negative vacuum pulls oil into the combustion chamber through the leaking seals. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net
