Author Topic: Low/no oil pressure (Read 4848 times)

rallydiesel · « **on:** December 23, 2007, 12:07:06 pm »

Rebuilt the engine this winter in our 91 1.6TD. Immediately after, the oil pressure buzzer would go off. I installed a oil pressure gauge when I rebuilt the engine. It shows about 0 - 2 PSI pressure. I am now using the same oil as before the rebuild. Drove the car for several months before the rebuild and never had the warning light/buzzer come on.

I just replaced the oil pump with a 36mm one and still no oil pressure. I am thinking there may be an obstruction somewhere between the pump and the sensor, causing oil to be diverted out of the pump relief valve.

My questions are:

Are oil coolers known to somehow plug up?

Where is the oil filter bypass valve located?

On the block, is the oil passage from the pump the top hole or the bottom one where the oil filter stand attaches?

rallydiesel · « **Reply #1 on:** December 23, 2007, 01:13:04 pm »

Quote

Sounds like you have an incorrectly sized bearing or didn't install one. You remembered the oil pump shaft bearing? The seal in the base of the vac pump shaft? Intermediate shaft bearings are in? Do you have a turned crank and used STD bearings? The ball bearings are still installed in the ends of the galley holes in the crankshaft? All of the oil squirters are correctly installed?

What bearing are you talking about? I never took the oil pump bearing out of the block. The intermediate bearings are new as are all the mains/rods. What ball bearings are there? The oil squirters are correctly installed. If there was an obstruction between the sensor and the pump the oil pressure at the sensor would be low if the pump relief was shunting oil back to the pan.

I'm going to pull the vac pump and the oil filter stand/oil cooler to see if I can find anything obvious. There is nothing leaking at the vac pump base and the oil pump shaft is engaged in the vac pump key.

Vincent Waldon · « **Reply #2 on:** December 23, 2007, 01:25:59 pm »

My vote is: pull the vac pump and the valve cover and spin the pump with a 13mm socket and electric drill. You should quickly see oil flooding the lifters... if your problem really is just an obstruction between the pump and the sensor channel.

For sure, you really don't want to be running the engine as you troubleshoot.

There are two places to check oil pressure... probably wise to get your pressure gauge on both of 'em... again while spinning the pump manually. Might help you isolate the area.

Another thought: you upgraded to the 36mm pump... are you completely sure it's being driven correctly by the bottom of the vacuum pump ?? You may need to pull the oil pan, timing belt, and then spin the IM shaft by hand while watching the oil pump... particularly if you can get good pressure with an electric drill.

Other random thoughts: New pump came with both gears ??!!! Bottom of the vacuum pump all chewed up ?? Tried a new oil filter ?? Absolutely positive you installed all the bearings ??

rallydiesel · « **Reply #3 on:** December 23, 2007, 02:01:19 pm »

Quote

My vote is: pull the vac pump and the valve cover and spin the pump with a 13mm socket and electric drill. You should quickly see oil flooding the lifters... if your problem really is just an obstruction between the pump and the sensor channel.

For sure, you really don't want to be running the engine as you troubleshoot.

There are two places to check oil pressure... probably wise to get your pressure gauge on both of 'em... again while spinning the pump manually. Might help you isolate the area.

Another thought: you upgraded to the 36mm pump... are you completely sure it's being driven correctly by the bottom of the vacuum pump ?? You may need to pull the oil pan, timing belt, and then spin the IM shaft by hand while watching the oil pump... particularly if you can get good pressure with an electric drill.

Other random thoughts: New pump came with both gears ??!!! Bottom of the vacuum pump all chewed up ?? Tried a new oil filter ?? Absolutely positive you installed all the bearings ??

I know I installed all the main bearings and the IM bearings. This is the second oil filter and second pump with the same results. Is there a gasket between the pump and the block? The manual doesn't show one but I'd think there would be? How many oil pump shaft bearings are there?

When I first filled it with oil it was -20 C and the oil pressure was about 25 PSI. As it warmed up, the oil pressure gradually dropped to 0-2 PSI. I guess I will have to pull the vac pump, filter stand, and pan and try turning the pump with the drill method to see what the deal is.

Pulling the pan at -20C is not fun :cry: .

rallydiesel · « **Reply #4 on:** December 23, 2007, 02:03:07 pm »

Another question:

Is the OEM high pressure sensor measuring pressure before or after the oil filter?

Vincent Waldon · « **Reply #5 on:** December 23, 2007, 02:50:03 pm »

Quote from: "rallydiesel"

I guess I will have to pull the vac pump, filter stand, and pan and try turning the pump with the drill method to see what the deal is.

Pulling the pan at -20C is not fun :cry: .

I hear ya.

You can start by only pulling the vac pump (one 13mm bolt) then spin and see what you get with your pressure gauge attached. And/or pull the valve cover and look for oil flooding the lifters. Baby steps... especially when it's cold ?!

No gasket between the oil pump and the body... or the oil pulp halves for that matter. Only one oil pump shaft bearing iirc... and it rarely wears bad enough to send the oil pressure to zero.

rallydiesel · « **Reply #6 on:** December 28, 2007, 09:49:16 pm »

How is it that the IM bearings affect the oil pressure so much? I am beginning to think that is why my 91 is having low oil pressure. I rebuild the engine and put in new IM bearings but they seemed tight to me. Maybe they should have been reamed first. Maybe they twisted and obstructed the holes. Libbybapa, you said they need to be oriented a certain way? which way? I thought the holes in the bearings were just to lube the IM shaft. Maybe the shaft is binding but wouldn't the timing belt fray very soon then?

My oil pump is new (36mm) and the timing belt is new and not wearing out. The IM pulley turns and doesn't appears to be slipping the TB but it is pretty much impossible to turn by hand but turns with a wrench on the IM bolt.

:?:

Vincent Waldon · « **Reply #7 on:** December 28, 2007, 10:01:40 pm »

Quote from: "rallydiesel"

The IM pulley turns and doesn't appears to be slipping the TB but it is pretty much impossible to turn by hand but turns with a wrench on the IM bolt.

That *does* seem quite tight to me.

Of course, tight is better than "loose and flakey" from an oil pressure perspective.

Vince

rallydiesel · « **Reply #8 on:** December 29, 2007, 04:54:40 pm »

Tried spinning the oil pump shaft with an electric drill today. Result: 8-10 PSI. Same engine temp running at idle: 2 PSI. The bottom of the vac pump where the oil pump shaft meshes with seems a little worn but I don't see how this would affect pressure much since the oil pump shaft still fits in well.

Am I thinking the IM bearings should have been reamed first and that is causing the problems. :cry:

subsonic · « **Reply #9 on:** December 29, 2007, 05:04:21 pm »

What kind of IM bearings did you use?

Vincent Waldon · « **Reply #10 on:** December 29, 2007, 05:22:15 pm »

Quote from: "rallydiesel"

Tried spinning the oil pump shaft with an electric drill today. Result: 8-10 PSI. Same engine temp running at idle: 2 PSI. The bottom of the vac pump where the oil pump shaft meshes with seems a little worn but I don't see how this would affect pressure much since the oil pump shaft still fits in well.

Am I thinking the IM bearings should have been reamed first and that is causing the problems. :cry:

I get 70-100 using the electric drill method (variable speed drill) so you certainly have an issue somewhere. Doesn't sound like it's related to the how the pump is being driven... can't remember if you've measured the end gap and gear lash on your pump ?? I think you said it's new... but...

In terms of IM shaft bearings: two types are available... one that needs to be reamed and another that doesn't. So, as a previous poster pointed out... you'll need to track down which bearings you bought.

Your IM shaft does sound tight to me... but to me tight bearings would not cause the large drop in oil pressure you are seeing.

rallydiesel · « **Reply #11 on:** December 29, 2007, 05:30:10 pm »

I got Dura-Bond bearings. Since I have read here that the finished ones tend to fit loose, I must have got the thick ones. This really sucks.

bigblockchev · « **Reply #12 on:** December 29, 2007, 06:30:03 pm »

I seem to remember someone having a problem with some kind of a different oil pump ie no oil pressure. If i recall the shaft was too short or something. Can you try going back to square one and reinstalling the original oil pump. maybe the pickup is incorrect, plugged, loose, missing, or the pump is borked. If all the bearings are all good then possibly it is somewhere in the oil pump system. Think about what is different from the original situation. Cheers Dan

rallydiesel · « **Reply #13 on:** December 29, 2007, 07:12:19 pm »

I had the old pump on there after the rebuild with the same problem. I remember putting the intermediate shaft in and thinking it was awfully tight. I had to tap it in with a mallet. The place I ordered the IM bearings from made no mention of the bearings having to be reamed so I just thought they were supposed to be tight. The old bearings were not flaking but I replaced them anyway since I had the engine out. Now I wish I had left them in.

rallydiesel · « **Reply #14 on:** December 29, 2007, 07:12:55 pm »

Anyone have a source for pre-sized intermediate shaft bearings in Canada?