Rebuilt engine, no oil pressure

crisbrady · 02-03-2011, 03:45 PM

I rebuilt my 89 2.7L NA engine this winter starting with a new block, and as commonly happens, can't get any oil pressure. I read tons of posts on here and Rennlist, and tried most of them without success. So I thought I post what I've done and see if anybody has any insights.

I've done the remove all plugs, dme relay and coil wire, primed the oil filter holes and crank the starter for 30 seconds, oh probably about 50 times now with no success. Tried the fire the motor route, that's worked for me in the past, but this time no pressure after 2-3 seconds so I killed it. I've removed and replaced the power steering pulley to make sure it wasn't cocked, the crank washer is positioned correctly, and the crank bolt is torqued to 155 lbs.

Yesterday I pulled the OPRV and it's not stuck, and moves freely. It's the one piece version. There was oil coming out from the hole when I pulled it, I assume that's a positive sign. The oil pressure sensor is brand new.

Tonight I tried a attaching a clear hose to the oil filter center tube and filling it full of oil. I then cranked the motor CCW by hand to see if I could prime the oil pump, but after a couple minutes of rotation, the oil level in the tube hasn't budged a bit.

Tomorrow I'm thinking of trying the 10lbs of air pressure in the dipstick tube while spinning the starter to see if that works. Worse comes to worse, I'll pull the oil pump and replace it with another but for obvious reasons - too much work

- I'll save that for last.

Any other suggestions out there?

rick13 · rick13's Garage

well...does the engine have plenty of oil in it?

John_AZ · 02-03-2011, 04:18 PM

Just pure guesses:

Did the oil pump match the new block? Early pump (5R) vs Late pump (9R)?
Last post...
Clark's Garage Message Board :: View topic - Rebuilt engine- no oil pressure

Oil pickup tube cracked?

Car not level?

GL
John

crisbrady · 02-03-2011, 05:13 PM

Yup, plenty of oil

Not an early oil pump, it came from an 89. Car is level, on a lift actually, and the oil pickup tube wasn't cracked.

Thanks for the link, I'll take a look.

HondaDustR · 02-03-2011, 09:24 PM

Try cranking with the OPRV removed. Seems like that's what did it for wildman who recently had the same problem, only it took both cranking and crankcase pressure to get it to finally prime.
http://forums.pelicanparts.com/porsche-924-944-968-technical-forum/579799-cant-seem-crank-up-any-oil-pressure-3.html

Wouldn't the center hole for the oil filter only lead to the bearings? The oil flows from around the outside of the filter element to the center, right? Maybe pour oil into the outer hole at the oil filter mount. It would have to fill the oil cooler before reaching the oil pump. Oil System Flow Diagram

rick13 · rick13's Garage

good question. where does the oil go when you put it in the center?

HondaDustR · 02-04-2011, 06:45 AM

It should go to the main galley through the block that feeds the main bearings and the cylinder head if the oil flow diagram is correct. The dirty side of the oil filter is always the outer side. The oil cooler is before the oil filter but after the OPRV.

rick13 · rick13's Garage

so just a myth in priming through the center tube...that's how i primed mine, i guess i just got lucky.

HondaDustR · 12:54 PM

Personally, I think so. I didn't pour any oil there after my rebuild and it primed just fine with a little persistence. It seems to take awhile because it has to fill the oil cooler, the oil filter, and all the oil galleys before it finally meets the resistance of the bearing clearances in order to develop pressure at the pressure sensor. Pouring oil down the center hole may help a rebuild reach prime faster, since the assembly lube will help keep the oil that's being added, going into the main galleys from just running out the bearings.

crisbrady · 02-05-2011, 02:48 PM

Well, removed the OPRV and tried cranking (plugs out) with and without about 15 psi applied to the dipstick tube, and no luck. So I guess the next step is to drop the pan and pull the oil pickup tube, re-check for cracks, and replace the seals, and then retry this stuff.

If that doesn't work, I guess I need to pull the oil pump itself off the block.

thanks for the tips guys.

John_AZ · 02-05-2011, 03:23 PM

When you assembeled the front crank pulleys, are you sure you put them on in the correct order? Could you have reversed one pully----flipped over?

Is the oil pump sleeve getting the tension it needs?

Again just a guess

GL
John

2Tight · 02-05-2011, 05:10 PM

Everyone has mentioned the usual suspects so I'll go wide. Any chance the new block was assembled with too much assembly lube? There have been more than a few people that have had this problem until the engine warms up and frees up the grease to flow...same goes for the Vaseline in the oil pump trick to prime it. Another possibility is the girdle not being absolutely flush with the block during assembly...it keeps the oil pump from priming if there is a gap that won't seal with the Loctite 574. Probably not your issue but can be another source of priming problems.

crisbrady · 02-05-2011, 06:19 PM

Quote:

When you assembeled the front crank pulleys, are you sure you put them on in the correct order? Could you have reversed one pully----flipped over?
Is the oil pump sleeve getting the tension it needs?

Anything is possible, but it's doubtful. Its not the first motor I've rebuilt, and I have the factory manuals and wasn't hurried at all during the reassembly.

Quote:

Everyone has mentioned the usual suspects so I'll go wide. Any chance the new block was assembled with too much assembly lube? There have been more than a few people that have had this problem until the engine warms up and frees up the grease to flow...same goes for the Vaseline in the oil pump trick to prime it. Another possibility is the girdle not being absolutely flush with the block during assembly...it keeps the oil pump from priming if there is a gap that won't seal with the Loctite 574. Probably not your issue but can be another source of priming problems.

I like your thinking, thanks. I was getting to the end of my tube of assembly tube and didn't want to go get another one, so I don't think I over lubed it. Didn't use any vaseline in the pump, so that's not a problem. And I remember checking the girdle and it was on nice and flush. Nice thoughts though!

commdiver · commdiver's Garage

I had same problem when doing a rebuild, and after trying all the usuall things still no psi! I took crank pulley off and checked the large crank washer and o-ring seal on oil pump gear, looked ok so I taped the gear and spun it with a hammer and large flat head! Then put it all back together and torqued with starter out and flywheel lock.

So then I bit the bullet knowing I had assembly lube on everything and started and ran it for about 35 seconds at idle and it finally caught pressure. At idle with plenty of oil or assembly lube less than 1 minute is not going to kill the thing? You might want to try filling both sides of oil filter housing, also I know its killing a good new filter but I have heard of guys using a newish filter with a tiny hole drilled in it to relieve air gap while running engine. Once oil psi builds it starts leaking then you obviously have a watcher with rag and kill it then install new filter?

matty89 · matty89's Garage

i suspect that the oil pump has something to do with it or you have a pinch'ed oil cooler hose that is blocked

ace_944 · 02-06-2011, 06:33 AM

Did you forget to install the oil pick up tube seal?

crisbrady · 02-06-2011, 03:35 PM

After pulling the front apart I think I know what the issue is. Here's the crank with the oil pump. Looking closely you can see the toothed sleeve isn't flush but sticking out about 1/8th inch.

Here's a pump from my used parts collection. The sleeve is flush with the seal.

So it seems that the toothed gear is not cleanly engaging the gears of the oil pump. It's either cock-eyed or jammed. I could have sworn it was all fine when I put it together, but that was 2 months ago.

So any suggestions on how to fix this other than pulling the motor from the car?

HondaDustR · 04:59 PM

I don't think it's supposed to be flush. All the ones I've seen stick out a little bit like in the first picture. You don't want anything to rub the oil seal. If you have one that's flush, it doesn't rub, and everything lines up and works fine, then I guess it's no big deal. Does anyone know if there are two different oil pump drive sleeves to go with the early and late oil pump? Maybe a sleeve mismatch.

Edit: actually after looking at the second picture, that pump appears dismounted from the engine. If so, the sleeve is probably bottoming out on the edge of the drive splines. On an assembled engine, the sleeve stops against the crank journal on the end face and not against the oil pump gear and the ends of the spline slots. The pressure of the crank bolt squeezes the sleeve against the crank and that's how it is driven. It's essentially what the crank bolt is torquing against, and also why it's so important to torque to 158 ft lb.

crisbrady · 03:44 AM

You're correct, the 2nd pic is of a unmounted pump, that is on my work bench. What you are saying makes sense. So it sounds like what I have is correct then. So no resolution then.

I guess the next step then is to drop the oil pan and verify the integrity of the oil pickup tube and seals. Just to rule them out.

_Van · 02-07-2011, 03:57 AM

You said the OPRV is the one-piece style. Do you know that there is also an early and late style - one is longer than the other... An early one-piece OPRV in a late block will not seal properly and will not make oil pressure.