99 dodge durango suv 173 k on clock. Has missfire code on #4 cylinder. Compression test 25 psi. 85- 90 % leakage mostly out tailpipe. Remove intake manifold rockers and p rods- retest leakage.Now 20%. To me this is an overpumped livter. Is it ok to replace just the lifters on this cylinder or is it better to do cam and all lifters?
1999 Dodge durango suv 5.2 litre
All details are in prior letter
Hello, A overpumped lifter is most likely not your problem. If you take rockers off do leak down test an it is escaping out exhaust? you have a vleve problem. The edge of the exhaust valve is either burned, bent valve stem or possible head gasket but most likely the valve itself. I would not waste $ on lifters, your problem is more than that unfortunately.
It seems I didn't describe clearly enough in my letter what was happening
I took off the intake manifold rockers and pushrods
before any dissassembly compression was 25 psi cranking and 90% leakage
leakage was mostly out the tailpipe.I put rubber glove over tailpipe to show customer the difference in rate of leakage vs oil filler cap opening
After I took Intake Manifold,rockers and pushrods off IE valves closed on that cylinder,leakage went down to 20% with very little out tailpipe.
I need to know if just replacing the lifters on that cylinder will get decent service life out of this kind of engine with this many miles or do I need to do cam and lifters?
Inspect the base of the old lifters very carefuly. If they are at all cupped, no matter how slight, you need to do the cam as well. If you confirm the lifters are 100% flat on the base, you can do job without camshaft replace. You will get normal remaining service life on cam and liftes, Just be sure you use the best straight edge you have to check the base of the old lifters, If one, is concave, putting a new lifter in will more rapid cam and lifter wear
after closer inspection, This is a roller lifter design so the lobe/roller contact wear should not be an issue,?
It can be. You need to be sure the roller is 100% flat all the way across and around. If any wear, now ones will not conform to cam correctly
ASE Master Tech, 32 years Diag/Electrical Specialist