New engine startup- no oil pressure

[Tom #16]

I just reinstalled by rebuilt engine. I wanted to get the oil circulated before I started the engine so I removed the plugs and disconnected the injectors. When I turn over the engine, I don't see any oil pressure. I removed the oil filter and poured oil down the center hole to prime the pump but it didn't make any difference. I looked inside the cam tower and I don't see any oil in there.

 

I'm pretty sure the oil sender is okay. I measured the resistance and it's 10 ohms, like the manual says. If I disconnect the leads the oil gauge goes off the scale, which is what I'd expect. When I just turn the key to the on position without turning the engine over, it doesn't go up to 5 bar- I thought that it normally does that but I can't remember.

 

Yes, I did fill it with oil- almost 6 qts.

 

Am I missing something?

[legoland951]

Are you sure the crank pulley bolt is torqued properly? Also there is a spacer/washer in there that is pressed against the oil pump making the oil pump turn when the crank is turning (if the crank bolt is torqued properly).

[Weston]

Chuck had the same issue. I believe he ended up pulling the oil filter off and putting compressed air through the dipstick tube until oil shot out through the filter... then it started pumping oil and making good pressure on it's own.

[Tim Comeau]

Tom,

It took quite a while of turning our last new engine over to get oil pressure.

I've heard of guys putting the car in gear and actualy towing the car around to fill the system without cranking the engine.

Where can I read more about priming the pump by putting oil in the filter hole, or by using compressed air in the dipstick tube?

[Tom #16]

I'm beginning to suspect something wasn't assembled right.

 

I'm surprised the shop manual doesn't give a good method to do this.

[ernie j]

When We build engines, we prime the oil pump, either before its installed or after. 944 engines we pour oil into the pick-up and crank the engine by hand. Then install oil pan. It works everytime, oil pressure right away, after installing engine on the dyno, after a few cranks. Hope this helps.

[Tom #16]

Are you sure the crank pulley bolt is torqued properly? Also there is a spacer/washer in there that is pressed against the oil pump making the oil pump turn when the crank is turning (if the crank bolt is torqued properly).

 

Everything is turning (cam and balance shaft belts), so I think the bolt has been torqued. However, I see a space between the seal and the camshaft drive gear. I should see a washer there?

[legoland951]

I doubt you will be able to see the washer behind the gear but there should be one. Without it, your oil pump won't be turning.

[944-Spec#94]

Right process or not this is what I did on my last few builds.

 

Build the engine using assembly lube. I put lots over the bearings down low. This stuff is stickier than oil and designed to stay on the bearings to lube at start up.

 

 

Pulled the coil. Wire so no spark.

 

Cranked engine over on the starter a for 30 seconds or so. No more. I never saw pressure doing this however.

 

Put coil wire back on.

 

Started engine normal. No pressure at start, but it built up in 30 seconds or so.

[Tom #16]

Joe:

 

So idling without oil pressure isn't a problem- it's under load that bad things happen if there's no oil pressure?

[944-Spec#94]

Joe:

 

So idling without oil pressure isn't a problem- it's under load that bad things happen if there's no oil pressure?

 

Well no.

 

Idling should bring to oil pressure however. It may take a few seconds to generate pressure on fresh build. It should come up to 5 bar in less than 1 minute. Really should be less than 30 seconds. The main purpose of the assembly lube is to provide lube before you build oil pressure.

[Chuck T.]

Chuck had the same issue. I believe he ended up pulling the oil filter off and putting compressed air through the dipstick tube until oil shot out through the filter... then it started pumping oil and making good pressure on it's own.

 

Yep easy easy easy ...

 

Just remove the filter and put air in the dipstick tube "whoosh whoosh" Oil everywhere !

[Weston]

Chuck had the same issue. I believe he ended up pulling the oil filter off and putting compressed air through the dipstick tube until oil shot out through the filter... then it started pumping oil and making good pressure on it's own.

 

Yep easy easy easy ...

 

Just remove the filter and put air in the dipstick tube "whoosh whoosh" Oil everywhere !

 

This coming from the guy that once said to me, "man, you really like to make a mess!"

[Tom #16]

I pulled off the crankshaft pulley and the thrust washer is there. So I decided to give Joe's procedure a chance. I started it up and let it run for a minute. Still no oil pressure.

 

I also tried pulling a vacuum from the center tube in the oil filter but air seems to be coming from somewhere so no oil is drawn up.

 

How about the oil pressure relief valve? Can that be screwing something up? I removed it and it went back in with no problem.

 

Anything else to do? I would do the air into the dipstick thing but I don't have a compressor.

[greg f]

When the girdle was installed onto the main block did it have a even coat of 574 sealant? Do you have the engine type number, ( stamped on the block right near the speed sensor bracket), as this would help identify which OPRV should be installed. Were any oil galley plugs removed during rebuilding? The 944 oil pump is a positive displacement pump, if oil is in it...it will pump it, but they are difficult to prime sometimes. Can you pull out the oil pump drive gear by hand, and does it slide in all the way when inserted into the oil pump housing? Greg F

[Tom #16]

Greg:

 

The engine number is M44/07, 43F 01422, which means that it's an 85+, right? My car is an '83. My original block had scratches in the bore. Since putting in cylinder liners is against the rules, I got a different block. So it looks like I have a late model block with an early model head and OPRV. Is having an early type OPRV with a late model block a problem? I don't know if the oil cooler is early or late model (or if they are different). I don't know about the oil galley plugs- I'll ask the builder.

[944-Spec#94]

Tom,

I posted a thread a few weeks ago about OPRV's. The cut off between styles was sometime in the 87 model year.

 

Let me see if I can get the model year from that number.

[944-Spec#94]

Greg:

 

The engine number is M44/07, 43F 01422, which means that it's an 85+, right?

 

According to the codes 43F Denotes 85 and M44/07 means later model.

 

So it is an 85.5 engine. It will use the same OPRV as and 83. So it can used a 3 piece valve or the 1 piece "replacement' OPRV valve.

 

The early head should not be a problem as I run a late head on and early block. They are all the same except for detail differences.

[944-Spec#94]

Tom,

Here is a schematic of the oil flow.

 

If you are not getting oil pressure it could be the following.

 

 

1) Oil pickup tube or girdle leak (must seal mating surface to block with 574)

If it there is an air leak the pump will suck air and never get oil.

 

2) Oil pump, leak (again sealing surface), or drive ring washer

 

3) OPRV ( However at cold start it would take the OPRV to be way off. Most of the time it causes too much pressure. A bad OPRV stuck open will show good pressure at start, but very very low pressure when warm.

 

4) Oil cooler, seals or the oil cooler itself

[Tom #16]

Thank for all the help Joe (and all you other contributors!).

 

I'm thinking there must be an air leak somewhere, because when I tried pulling a vacuum from the oil filter center coupling, I get air. If the OPRV is closed at cold, I should be able to draw oil in this way.

 

Something just occurred to me. When I blow into the dipstick hole I can see air escaping from the oil filter center coupling. I don't think that should be possible if things are working right. This implies a leak somewhere between the pickup and the oil pump...

Edited July 5, 2007 by Guest

[944-Spec#94]

If you have to pull the bottom end apart take close look at the bearings. They should be fine, but far better to deal with them if you are in there just in case.

[JonnyCocktail]

When I rebuilt my engine, I had the exact same problem. It drove me crazy. It was due to the oil pump not being primed.

 

Here is what I did.

 

Remove the oil filter, fill the center hole that goes into the oil filter with oil and crank the engine BACKWARDS with the crank pully. Do this a couple of times and then reassemble everything and you will build oil pressure.

 

Trust me, I tried everything from redoing the entire oil coller assembly twice and it just turned out to be the oil pump not being primed.

 

Hope this helps!

 

Jonny C.

[Tom #16]

BTDT. I've put so much oil down that hole that it's overfilled now.

 

I did fix one problem. The lower O-ring on the oil trap was too small and didn't make a seal. This fixed the air leakage problem. Now, it simply seems like the oil pump is not pumping.

[JonnyCocktail]

Understood. But when you hand crank the engine backwards, does the oil get drawn into the pump?

[Tom #16]

No, not really. Sometimes it just seems to flow through, but it doesn't seem to be related to turning the crank.