oil pan removal: prior-to questions

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aalto

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I recently replaced the 3.0l engine in my coupe with a 3.5l engine from a 1987 e24. Everything went smoothly and the new-to-me engine was assembled with the 3.0l oil pan, 3.5l oil pump, and 3.0l pickup. Everything went well and i was ultimately able to get good oil pressure and start the engine without problems. I ran it for perhaps 10 minutes during which time the engine was quiet and smooth (once i got the timing and webers sorted out).

The next day i came back to the car, went to start it and . . . no oil pressure at all. Swapped the pressure sensor with no change and verified the absence of oil at the head by removing the valve cover.

I'm pretty confident the problem is with the oil pump itself OR the oil pump tensioner. The tensioner is the later spring-loaded gadget (from the 1987 block). The reason i'm concerned about it is that during dis-assembly I needlessly tried to remove the nut on the oil pump gear with an air gun and had the tensioner (or at least the metal spring it contains) come apart. I re-assembled it and couldn't see any problem with it however now i'm concerned that it was actually broken somehow. I'm also now questioning is using the new (1987) oil pump and old (1974) oil pickup was the right thing to do! Maybe the problem is actually in the mating of these two things.

As this point i'm getting ready to remove the oil pan and take a look at what might be wrong. I have two general questions for the board:

1. Is there any other thing that could cause a complete loss of oil pressure that i may have overlooked?
2. If i do have to remove the oil pan to rectify the situation (and i'm pretty sure i do) what is the best technique to do this. I'm assuming that the engine would need to be lifted slightly but even if i did that i can't see how that oil pan is going to make it past the sway bar.
 
What filter housing?

Check the oil pressure relief valve in the oil filter head/ bracket. Make sure it's closed.

Then, plug the un-needed hole if you used the early bottom bolt filter.

There's a procedure for removing the pan in the manual. Best to jack it up first and support at the mounts. Then turn it to the position -number 5? or 6? crank/ rod down. Unbolt the pump, etc. In other words, you get to do the hokey pokey. But doable.
 
Thanks guys,

I am using the newer oil filter assembly (top bolt) that came with the 87 engine so it should be OK. I did have it off the block after the problem developed and it appears to be OK (ie. closed).

I'm feeling like that pan needs to come off. Nice to know it is possible if not very enjoyable.
 
Had a bit of time this evening and dropped down the oil pan enough to see the tensioner and chain. Everything looks fine. Also took the filter assembly off again and double-checked that the relief valve wasn't jammed open.

Since I've gone this far I guess I'll lift the engine up and pull out the oil pump and pan. Strange that it would completely fail though! A bit baffled by this whole episode.
 
Make sure the sprocket nut didn't back off. Later oil pump sprocket nuts are notorious for this.
 
Thanks again for all the help. Sven, you were correct! I took the filter assembly off for the third time (!) and looked closely for that hole. Sure enough, there it was.

Having some pressure the first time i started the car put me off the track. What i think happened is that the narrow slot that the oil passes through to reach that hole had been filled with crud over the years and allowed the engine to pressurize. However after a second start the "dam" of crud broke allowing all the oil to flow back into the sump.

What is worth noting for others who might be doing the 3.5 swap in the future, is that the thing that caused this problem was the change to the to old (1974) oil pump pickup. The 1987 pickup actually has a corresponding hole and a built-in pressure relief valve. This newer pickup is meant to pair with the the newest style oil filter housing (the one that is very easy to change filters on) that doesn't have a relief valve built in. What confused me was that someone had converted my particular engine to the older style top bolt oil filter housing which actually does have the relief valve.

Hope this makes some sense . . . sorry for the convoluted story.
 
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