rdjeep Posted December 19, 2014 Share Posted December 19, 2014 I have a very recent & rapidly declining oil pressure issue on an otherwise healthy engine at 126,XXX miles. Cold engine starts at 33 psi @ 1300 rpm, but I can watch it drop to down around 5 psi @ 800 rpm only a few minutes later. Is there a common/typical issue that crops up? Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 19, 2014 Share Posted December 19, 2014 Yes. It's common for the screws on the backing plate of the oil pump to loosen and back out. This causes the backing plate to separate from the pump and oil pressure is bled back into the crankcase. Have to remove the oil pump from the block to fix it. If it needs a timing belt, nows the time to do it. Quote Link to comment Share on other sites More sharing options...
upnorthguy Posted December 19, 2014 Share Posted December 19, 2014 Beergarage has a nice write up of what Fairtax describes here. Also, great vid by Miles Fox . Quote Link to comment Share on other sites More sharing options...
ivans imports Posted December 19, 2014 Share Posted December 19, 2014 Check thrust bearings for play Quote Link to comment Share on other sites More sharing options...
Gloyale Posted December 19, 2014 Share Posted December 19, 2014 +1 oil pump back plate coming off. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted December 20, 2014 Share Posted December 20, 2014 +1, most of them i've pulled have multiple screws loose, yours must be all of them. nice catch - how did you catch this? noise? Quote Link to comment Share on other sites More sharing options...
xdeadeye1 Posted December 20, 2014 Share Posted December 20, 2014 I just did my timing belt,, I had at least 3 screws loose in that backing plate. Quote Link to comment Share on other sites More sharing options...
rdjeep Posted December 23, 2014 Author Share Posted December 23, 2014 Thanks for all the replies and links! Figures, I just was in there doing the water pump. I'll drop a line when I get to this next week. At least the weather will be pleasant! Quote Link to comment Share on other sites More sharing options...
rdjeep Posted December 27, 2014 Author Share Posted December 27, 2014 Good call.... all but one screw loose. Annoying the factory never used Loctite on them. 65 psi at 1500 cold rpm, 55 psi at cold normal idle. The Felpro kit's gasket instead of the sealant is a good idea, too. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted December 28, 2014 Share Posted December 28, 2014 55 is low for cold pressure. It should be above 70 at cold idle. Bypass valve pressure is 75psi so you should get close to that. What pressure do you get at warm idle? You didn't put a gasket on the backing plate did you? Should be no gasket there. A gasket will increase the clearance between the pump rotor and the housing and will lower the output pressure. Quote Link to comment Share on other sites More sharing options...
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