I was replacing the timing chain in my 304 this weekend, when I pulled the timing cover I couldn't help myself but had to inspect the oil pump. Now I've noticed that the oil pressure has been down a bit. Kinda happened over a short period, I could almost say soon after the last oil change. Anyway I noticed pitting on the face of the gear teeth, the housing itself showed a little wear where the gears ride but not too bad. When trying to remove the relief valve I had trouble getting it out. The bore was gumed up with a tar like mess, made me wonder if it could have been sticking. I ordered a rebuild kit and plan on putting the new gears in with maybe some machinest dye to check the wear pattern in the housing. I think I'll also check the clearance with a plastigauge. Does anybody know what the tolerance should be? Also what are the dots or holes on the gears for? Also, at last oil change I used a Fram oil filter. This seems to be frowned upon in AMC circles, anybody know why? I've used Fram for years never had a problem but as I mentioned above it almost seems like my pressure dropped a little soon after I changed oil.
304 oil pump questions
- Thread starter flatie46
- Start date
an oil filter is an oil filter, the vehicle manufacturer specifies the microns needed to be filtered; the filter manufacturer complies with that; my only assumption is that Fram does not ahere to the specifications of what AMC required. Dunno.
as for the tolerances and wear, what is the gear made of and what are you rinnung for a cam. depending on teh cam, some manufacturers will spec a brass gear or some other type of metal. if your using brass and it should be steel, it would prematurely wear.
as for the tolerances and wear, what is the gear made of and what are you rinnung for a cam. depending on teh cam, some manufacturers will spec a brass gear or some other type of metal. if your using brass and it should be steel, it would prematurely wear.
Jester32
New member
Actually an oil filter isn't an oil filter. Cut a oem filter then cut any jobber a wix. Fram. K&n. Don't matter the filter media is way thinner. There is a substantial less number off pleats. The bypass valve is of poor construction and often fails and allows un filtered oil through. I Will only run oem filters. I would rather reuse a filter than run a none oem.
Well, the gears are steel but are in the aluminum timing cover/oil pump housing. The steel gears will wear the housing, mine shows a little wear but I don't think it's to the point it needs to be replaced. I know from working on gear pumps at work you can close the tolerance up ( to a point of course ) and gain pressure. I think they even make thinner gaskets for the pump cover to get the right clearance. This info may come in the rebuild kit. If it doesn't, that probably tells me I didn't get much of a kit.
Saddle Tramp
New member
I have honestly never cut a filter apart. I've been running Fram filter (as in cheap walmart fram filter) in my pick up since 36K miles (when the dealership stopped the oil changes) and I am approaching 205K miles, still have great oil pressure and I recently had to replace the rear intake gasket/seal (common vortec chevy issue) and I saw no evidence of excessive sludge buildup. During oil changes, I use the old oil to lube the new filter gasket and it has never been gritty.
I am not doubting you, just simply not my experience.
Jester32
New member
The thing is. The oil should never have much more than some small metal particles on a properly maintained engine. Sludge etc will never develop if it's not allowed to. Proper warm up is important. Etc. It's the small metal particles that get through the filter that cause damage. Oh and I love the vortec. My last one had 505 000 k on it.
505 000 k ??? for us americans?
JK
it's a 98 gmc 1500, I've owned this truck pretty much since new, it was my fathers and he sold it to me after 2 years and 10K miles because he wanted a new, duramax.
I plan to put about another 50K miles and then I will be exempt from emissions and I'll drop a 12 valave/nv4500 combo in.
JK
it's a 98 gmc 1500, I've owned this truck pretty much since new, it was my fathers and he sold it to me after 2 years and 10K miles because he wanted a new, duramax.
I plan to put about another 50K miles and then I will be exempt from emissions and I'll drop a 12 valave/nv4500 combo in.
Thanks, that helps a bunch. Gonna try to get it back together this weekend if I don't hit any snags. I don't know anyone locally I can question about AMC engines. The forum really helps.
Because I have a 12 valve, plus no need to bother with all the electronics and such
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