Rxmfn7

iTrader: (4)

I had a thread a few weeks ago on an oil pressure problem on my '90 GXL. Symptoms are as follows: Startup, oil pressure goes to ~45psi,( ~1500rpm) holds steady there until car is warm. Once warmed, and idle is stabalized at ~700RPM, oil pressure will drop slowly, until almost 0. Once warm, oil pressure will be ~30psi at 1500 RPM, and reach a max of ~55psi at 4-5k rpm, and not go above that pressure the entire way to redline. This has been verified by an aftermarket mechanical gauge also. Since there can be a few causes of this, I replaced just about everything in the oil system I could think of. This included, replacing the e-shaft thermovalve with a solid pellet, as well as the spring behind it being replaced. Also installed a new OEM oil pressure regulator ( rear housing, under oil pan), as well as a new bypass spring in the bottom of the front cover. Also replaced the front cover o-ring, as I thought that may had slipped out. All this, and there is zero change in oil pressure, I am still having the same problem. The only thing I havent replaced is the pump itself. Has anyone had the pump go bad, and if so, was it having symptoms like this? I hate to just hang parts on the car without a definite diagnosis, but right now, I am stumped. A new pump/chain from mazdatrix will run me close to $200. I hate to spend that, as well as the time replacing it if Im not sure that is the problem. Any insight would be greatly appreciated.

Also, just for some background info, this engine has only about 8k miles on the rebuild/streetport, done mby JR rotary in NJ. ( Judge ITO).

ddub

I think you remember my oil problems I was having as well. During the tear down of the front cover and inspection I checked the pump to see if it was within spec via the FSM. Mine certainly was not! I had some spare pumps and used the best parts from all of them to get it within spec. You need to use those feeler gauge things to check for space between parts to see if it's in spec. Needless to say with all the things I changed it was fixed.

Next thing for you that I'd try would be the oil pump, oil pump drive gear, and possibly the gasket for the pickup tube (have you checked this?).

I kept my chain the same too when I rebuilt the pump so to speak, and it was fine. I see 30psi at idle now and 75+ after 4-5k rpms. Cold idles I see 60+ at idle till warm. This is with an 85psi OPR, though. Before buying anything else, check the oil pump with feeler gauges and check the oil pickup tube to make sure the gasket is still okay there. That way you can avoid buying anything else until you confirm those things are indeed bad. You can always try and pick up a n/a or TII (for an upgrade) good condition oil pump from someone else on the forum, or buy like 3 used ones for cheap and do what I did and rebuild them with the best parts from all. The FSM shows how they come apart/go back together and it's fairly straight forward. Just don't lose the tiny woodriff key I almost did and that'd be bad!

Rxmfn7

iTrader: (4)

Yes, I did check to see that my oil pickup tube gasket was in place, and it was, and in good shape. I did spec out all the springs I replaced, and they all were slightly out of spec, but I guess it didnt make very much of a difference. I am kicking myself for not replacing( at least checking out) the pump while I had the front cover off.. I was just so sure it would be a 0-ring or spring problem. A bad pump honesly didnt cross my mind at 1st, just seems I have never even heard of people having issues with them. Do you think the pump was your problem, or did you find something else when you tore it down?

ddub

The pump had to have been ONE of my problems, but I had multiple ones. There were more than a few things out of spec, and the pump was pretty bad, so I'm pretty sure it was helping the issue. But I honestly can't say if it was one of the deciding factors since I did everything at once. If you have the time I'd at least check it to make sure it's in spec or out of spec before buying anything. That IS if you have enough downtime possible of course.