dizzyj

No balance shaft covers. Nothing leaking from there. Pickup tube was reinforced. Engine is almost out of the car, will know soon

Humboldtgrin

In the past my pick up tube broke on a stock 2.5 with balance shafts. Your may have broke due to vibration because you deleted your balance shafts and have huge displacement! It sounds like everything else is fine. OPRV don't usually just stop working all the way. Before ordering a very expensive OPRV, drop the oil pan and check the pick up tube. Also if your stil running a stock fuel rail you better upgrade to a billet one again due to vibration the stock one will start to leak. Mine did on my 951 out of the blue one day and I'm mostly stock.

dizzyj

update:

Dropped the engine and pulled the pan.
good news:
- cam looks good
- #2 bearing / journal looks good
- pickup tube looks good.
- freeze plug near #1 looks good.

so no catastrophic damage.

Bad news:
- no smoking gun.

Next, pull oil pump, check seating surface between girdle and block.

ill do that and try another oprv.

refresh951

Do the squirters look good?

dizzyj

still need to look at that. Ill either have to pull the pistons or see if I can see them with a boroscope.

rlm328

You have a solution yet?

dizzyj

Was re-installing the engine this weekend, when under the cam tower gasket we noticed some metal shavings (looks like machine work). So we dropped the motor and did a full tear down.

Most everything looked good, but will make sure and do a full clean before re-assemble.

2 things I noticed, and I think they might be related:
1) Previously I had a problem with my front oil gally plug. The machine shop threaded it and it leaked. While everything was torn down, I noticed that the plug is pretty deep and blocks a good bit of the passage to the mains.
2) I'm using the acl rod bearings, which are brown in color. on most of the rod bearings the brown is wearing away to some degree (no galling). I dont know if that is normal. I only really idled the engine and drove around the block a few times.

The current plan is to re-clean the whole block, plug the gally holes with aluminum threaded plugs that dont block anything, then re-assemble.

URG8RB8

I am surprised nobody asked this question previously. Are you using the stock oil pressure sending unit and gauge in the dash? Mine died right after a HG replacement and scared the Hell out of me. I thought I managed to screw something up, but just replaced sender with new VDO solved the issue. Do Not use one of those cheaper brands, that gave me a double scare me because I had a dead one right out of the box which made me sure I did something wrong.

Tom M'Guinn

He said in the first post that he confirmed no pressure with a manual gauge (meaning a good old mechanical gauge I presume....)

URG8RB8

Oh, sorry missed that, still hard to read on this new App, not like the old one that doesn't work anymore.

refresh951

My bearing on my 2.85L showed no signs of wear what so ever. Sid has some pics of his 2.85L ACL bearings on here. They also were perfect after 10K miles. What was max runout on your crank? What was your rod bearing oil clearance?

Was oil pressure fine and then suddenly dropped to zero? If so I do not think any of the above is the reason. Did the squirters look good?

dizzyj

I agree that none of this was the cause of oil pressure drop. and after having completely disassembled the engine, I have not found a root cause. Frustrating, but it is what it is.

I dont remember runout of the crank. the crank guys said it would have effectively 0 runout. I did not measure myself. I used a very experienced crank shop that several race shops recommended.

the squirters look great.

in a positive note, it did force me to completely rip apart the engine and find some potentially catastrophic things that I would not have found otherwise.

Humboldtgrin

Ok did you align the OPRV housing? If you don't use the alignment tool the o ring won't seal right on the block and will loose pressure and prime. Also look at the seat on the block, down that little hole, for the OPRV were the o ring seats. You may have corrosion on the seat. If that's the case you may need a new block or machine the seat a little tiny bit and use a little bigger o ring. Also pump fresh oil down that hole before installing the OPRV to prime the oil pump. I had this problem on my 86 944. My 87 951 had the broken pickup tube. My 86 944 also has a one piece OPRV because the walls are corroded where the three piece OPRV was sticking on the walls. And I know you have the right OPRV, but make sure your not using an 86 and earlier(o ring at the tip) OPRV for the 87 and later blocks and vise versa. Just have to throw that out there.

dizzyj

Update:

after stripping the engine and finding some metal shavings in the bearings, I did another rebuild.

This time I cleaned and pressurewashed the block inside and out.

all new bearings, new ovpr o-ring.

Tonight, I primed the pump and was able to get ~4 1/2 bar of pressure on my manual gauge. Factory gauge still read 0 (with the light off). This was the same symptom that caused me to initially freak out (factory gauge read 0).

So, I think the smoking gun must be wiring/sender/gauge. That said, it was probably a good thing i tore the block down, cause the bearings were shot.

Jay Wellwood

...a silver lining in every cloud