Thread: Low oil pressure

Few drops of oil won't lower oil pressure. It's got to a big gusher bleeding off almost all the pressure. If you were one of my customer, the installation of a manual oil pressure showed low pressure at normal engine temp.. No internal engine noise...small oil leak around the oil pressure feed / timing cover. No sludge in the valve train area... Recommend removing the timing cover for inspection.

afe18db2-548b-4189-a68e-7d4f366dee32_zps13a3e268.jpgc38eba03-151b-4f5e-ad9c-0010aed04cb7_zpsaf1a8d59.jpgFirst image show the backside of a 3.8L V6 timing cover. 1st image, the high pressure oil passage in the vertical long oval. Only thing that seals high pressure oil coming out of the timing cover into to front oil galley / engine block is a paper gasket. Inspect for a failed gasket or cracked t-cover.
Second image is t-cover with the oil pump gears and outer plate removed. Check where the gears ride against the aluminium t-cover for scoring. Excessive scoring will decrease the amount of volume and pressure the pump puts out. Right of the oil pump is the oil bypass outlet. The bypass can fail allowing the oil to be diverted out the hole into the timing chain area.

Hope this helps. Ted

Well I finally had some time to pull this thing apart and here is what I found:

A. I think my oil leak is out the front seal around the dampner judging by where I saw oil leakage, but the seal is not visiblily damaged like the one tomtom123 posted. I've inspected the timing cover for cracks and I don't see any thing. Obviously I'll putting a new seal in.

B. Somebody has had this timing cover off fairly recently probably chasing the same thing I am. The gasket looks fine unfortunatly. I will scrape it off and put a new one anyhow to be sure. Should I put a new timing chain in while I am here? Is the Cloyes C381A as good as the original or would I be better off leaving the 153K mile one in there?

C. I took the oil pump apart and it visually looks fine. I'm going to go ahead and install the Melling K195 oil pump repair kit anyhow.

I suppose my next step will be to drop the pan and look at the sump.

Someone may have been trying to repair a leak in the tc. Possible debris, gasket material, rtv inside the oil pan? I would pull the pan next. If the screen is being restricted, clean or replace pickup screen. Reassemble with new t-chain assembly and tensioner. Install new oil pump gears, pack gears with petroleum jelly (primes pump). reassemble tc. Retest oil pressure.
If oil pan and pickup are clean...lets hope you find the trouble in the oil pan.

Ted,

I would say that the aluminum timing cover does have some scoring in where the oil pump pieces rotate. Do you run into that sometimes and have to replace the whole timing cover? Thanks for your very detailed help!

I want to give you good info on diagnosing this oiling problem. Some scoring should not be causing such a loss of pressure. Inspection of the oil pan and pickup is necessary. Check for metal debris inside the pan, or something restricting the oil pickup or air entering the supply feed.

The pictures I've been using are from a 99 gtp with a spun rod bearing / damaged #3 journal. It left a pile of debris inside the pan and scored oil pump housing/timing cover. Also worn cam and balance shaft bearings.
Oiling system- oil pump is supplied oil directly from the oil pickup screen inside the oil pan. Any debris is going srraight into the oil pump unfiltered. Scoring of the aluminum oil pump housing is very common.
Hopeful your engine is going to be ok and it's a problem with the oiling system only. Ted

I put a new oil pump in it and it felt a little tiny tiny bit tighter than the old one, but after putting back together and driving it, that didn't improve the hot idle oil pressure any. It has about 26 psi at 1850 rpm going down interstate. I dumped a half bottle of lucas in and it seems to maintain 10 psi min at idle so that was a slight improvement. I blew air backwards through the pickup tube when I had the timing cover off, I sure don't think the sump is plugged up any if at all. Its got some pressure, I wish it was more, but I think it will live, I've seen some tired old small block chevys run for a long time with very little oil pressure.

Yea, this doesn't sound good. With 10 psi at idle it sounds like you are ~5 psi away from the "change engine" light coming on and you starting a quest for a low mileage long block. I'm assuming you pulled the pan to check the pickup for obstructions and the pan for debris that may get sucked up into the screen and block oil flow?

mrt23, it was very interesting following you trying to resolve the oil pressure problem. Hopefully your engine will last for awhile. If you decide to tear in the engine let me know what you find. Ted