64 replies to this topic

[koalasprint]

Hi All, I'm looking for help and suggestions to find out what's gone wrong my my new engines oil pressure. The engine is a 308 block with a 355 crank. Someone else did the block preparation and built up the short motor. I checked the main bearing clearances and got those up to spec. I also installed a flat tappet camshaft. (Crane CCH-314) But I didn't touch the cam bearings. I also installed the oil pick up and an ASR sump.

 

The engine was run in and tuned on a dyno eight months ago. Initially we had no oil pressure and the dyno guy fixed that by putting a smear of vasoline on the rotors and removing the excess silicone that the short block builder(idiot) used. Oil pressure was very good from then on.

 

Over the holidays I finally finished installing it into the car. I've run it a couple of times in the car to check for installation problems, etc. But only in short bursts as I haven't had the full exhaust installed yet. Oil pressure has been OK until yesterday. I ran the engine around 1500rpm for about 10 minutes to flush the cooling system and install proper coolant. Towards the end of this I noticed that oil pressure was almost zero. I shut it down and let everything cool off.

 

Next I drained the oil and it looks ok. No sign of any metal.

 

Pulled cover off oil pump, all looks ok there.

 

Checked gauge, shows full pressure when the wire is earthed at the sender. The sender reads 75ohm at no pressure and drops to 25ohms when I hit the hole in it with compressed air.

 

Put new oil in and new filter on.

 

Peeked into the rocker covers, they look a bit dry to me.

 

Started it again after the oil change, still nothing. Shut it down after maybe 15 seconds. I couldn't hear any excessive noise from the lifters, but hard to tell with no exhaust.

 

I went to take off the new filter and it was full of oil. I unscrewed the sender again and oil came out of there too. So I don't think that the pump or pick up are the problem.

 

There are no external sign of any oil leaks or problems.

 

I suspect that the oil is bleeding out big time internally somewhere.

 

Any ideas? What else can I test for?

 

I am worried that this is going to be an engine out job along with another set of gaskets, etc.

 

[8BALL]

Did they re-install the oil gallery plug?

The oil pick up hasn't broken off?

[S pack]

Check for a seized Pressure Relief Valve or weak or broken Relief Valve spring in the oil pump.

[Redslur]

Put a good remote oil pressure gauge on it to make sure it isn't a faulty gauge. If it hasn't got any pressure, pull the oil pump off, fill it with vasoline and reinstall it. Try to get oil pressure again. While the pump is off, check that the shaft to the cam is ok and not turning freely.  The oil pump gear can spin if the roll pin brakes or comes out, or the gear itself can wear enough for the engine to lose oil pressure.

[koalasprint]

Thanks for the replies guys, much appreciated. I'll have another look and try those things above. Not sure if I'll get a chance before I tow it to have the exhaust fitted, but I'll post an update when I have one. Again, thanks for taking the time to help me with your suggestions.

[orangeLJ]

Id be getting a good mechanical pressure guage on it first, you'll know straight away whether it's a non issue from that.

Should show pressure after cranking for a short period.
Did you cut the filter an look internally for metal fragments?

If it's still showing no pressure on a mechanical guage, I'd be starting at the oil pump and workin my way into the motor from there .

[koalasprint]

I did a bit more investigating last night. Plenty of oil in and around the pump and filter, so i don't think that the pick up is a problem. I checked the pump drive shaft it rocks a few mm but seems pretty solid. So that plus the oil in the pump eliminates that. Springs and relief valve moves ok. I tested my pressure sender with an ohm meter and compressed air. That checked out Ok. Reading moves from 70 ohms at zero PSI down to 15 at 60 PSI. I also put a resistor to earth and the gauge checked ok. Reading 3/4 pressure with a 47ohm resistor. I think that the next step will be as above, cut open the old filter and have a look, borrow a mechanical gauge and see what happens when I crank it over. If there is metal in the filter or no pressure with the mechanical gauge then I'll have to start taking it apart. I'm thinking to take off the inlet manifold and see if there's an obvious galley plug that's been pushed out. Thanks for the help and suggestions guys. Really appreciated.

[mick_in_oz]

Before I pulled anything major off I'd test it with a mechanical gauge, and if there is no pressure I'd put a good bit of vaseline in the pump and try it again, and only after this would I pull anything else apart, and yes I know you said everything is oily, BUT, Holden V8's hate sitting about, they even hate oil changes, and you only have to be a bit unlucky and you have no oil pressure.

 

Another thing you can do is to unscrew the oil filter a few turns and crank it (without any ignition) to see if its pumping oil into a container and if it is tighten the filter and crank a bit more, till it has pressure. This can be a good technique to help it quickly get rid of any air in the pump system.

[koalasprint]

Great tips and information there, thanks Mick. Hopefully you are right. One thing I did notice is that the oil pressure gauge is very slow to move with the resistor to earth. The other thing I want to do is move my engine to battery earth strap. At the moment it bolts to the cylinder head. But they are alloy, which doesn't conduct as well as iron. But I need to make up a longer strap to reach the block. The mechanical gauage is a must do test. The car is now off to have the rest of the exhaust made so I'll have to wait to try your suggestions. But I will keep all informed of progress. Thanks again.

[mick_in_oz]

If you are talking about the original gauges in the dash then yes they do move slowly, very slowly, they are a thermal gauge and the slow is a feature to "damp" or stop the gauge bouncing about from various things that can happen, cornering etc.

 

Aluminium is a very good conductor of electricity, no need to move the earth, and it wont help the gauge to read any differently, Aluminium is a MUCH better conductor of electricity than Cast Iron. The Power wires in the street that carry the power to your home are made from Aluminium.

 

If the Earth to the engine block was so bad that the gauges did not work, then you would never have been able to start the engine. The gauge might consume something like perhaps 1 Amp total, and the starter will be more like 300 Amps. You have already done a simple/crude but very valid go/no-go test by earthing the sender wire and found that the gauge does indeed move to full scale, it may not be accurate, BUT, it certainly is working, and working well enough to show engine oil pressure assuming it had any.

[koalasprint]

Yes I was talking about the original gauges. I never took much notice with the old 308. Maybe I should have.

 

 

I stand corrected regarding the conductivity of Aluminium and am happy about that! One less job to do.

 

Thank you Mick!

[koalasprint]

Just a quick update. Car is now off for exhaust fabrication so not much I can do until I pick it up. I pulled apart the old oil filter as suggested above. I only noticed two tiny specs of metal. I dragged a magnet over the filter medium, running it through the oil residue. Eventually the magnet picked up a bit of metallic stubble. But it doesn't look catastrophic, to me anyway. That filter was put on when it was run on the dyno. So it saw 6 or 7 decent power runs, plus the 10 minutes of running that I did at home with it in the car. When I get the car back I'll try a mechanical pressure gauge and the other suggestions above.

[Redslur]

Keep us updated mate.

[koalasprint]

Update time. I got the car back on the weekend after having the exhaust fabricated and fitted. I have borrowed a mechanical oil pressure gauge. With the plugs removed I cranked over the engine, no oil pressure. I took the gauge off the hose and cranked again, hoping to see oil squirt out the hose. Nothing. I hooked up a funnel to the hose and tipped in half a liter of oil. It slowly drained into the motor. Then I put the gauge back on and cranked again. Still nothing. I put some petroleum jelly into the oil pump rotors, but hard to get much in as it's been very hot and as soon as I touch it it melts. Anyway that did no good either. Next I'm going to put some suction onto the oil filter outer gallery and see if it pulls oil, air or blocked. Oil = good. Air/Blocked = pick up problem. Assuming I get oil I'll crank the engine by hand, holding the pump drive gear in situ and see if it turns. If not I've found the problem. If it does turn, I'll block off the PCV vents and put 5-10psi compressed air into the dipstick hole. Oil should come out of the oil pressure hole then I'll put the gauge back on and crank it over. If I get pressure I'll start it up.

Edited by koalasprint, 07 March 2017 - 10:13 AM.

[Rockoz]

Sounds like it may be sump off time.

Cracked pick up pipe or maybe even fallen off.

[S pack]

Just a thought, remove the oil pump and insert an appropriate sized flat blade screwdriver up into the end of the oil pump drive shaft in the block and see if the shaft will turn.

If you can turn the drive shaft with the screwdriver you have found the problem.

[mick_in_oz]

Yup, do what Dave has just said before pull anything more major off.

[gtrboyy]

Did you take oil pump off to pack gears full of grease?

 

That would be good time  to check oil pump drive with screwdriver.

 

Doubt blowing compressed air down dipstick is enough force oil through oil pickup tbh.

 

 

Have once seen someone dodge up fittings then use 2 litre container of oil & pressurized it to force oil through sender hole into engine before engine start up.

[warrenm]

when i cracked the gtr motor this what they did - old gas bottle with the air fitting and a hose where by they screwed on to the oil pressure gauge primed the system first put the gauged back and bingo.

I do it the same way except I use an old fire extinguisher.

[koalasprint]

I did check the drive gear by trying to move it by hand and it seemed to be engaged OK, but hard to put much force into it. PS Not using grease, just petroleum jelly. Will try with a screwdriver when i open it up again. Won't be able to do anything for another week though. Thanks guys for the suggestions.

[koalasprint]

I like both suggestions above to prime the oil system. Using the Ford pump with a drill makes a lot of sense.So I'll keep an eye out for a pump.

 

Today I did some further testing. I took off the pump and found that the gears are OK. They turn with the engine. With the pump off I was able to push a rubber hose into the block gallery that leads to the pickup. I was able to suck oil up and it slowly siphoned out. So I think the pickup is Ok. I wasn't able to get a good seal onto the oil filter outer gallery so I couldn't see if it pulls oil, air or blocked. I blocked off the PCV vents and put 5-10psi compressed air into the dipstick hole. Oil eventually came out of the oil filter gallery hole. I put the filter back on and tried the same thing, but no oil, just air. I suspect that the air is coming through backwards from all of the oil discharge holes as it is too hard to push through the pump and filter.

 

I wasn't able to rig up a bottle or spare pump to prime the system. Not enough bits on hand yet. So I put more oil into the pressure sender hole until no more would flow. I the gauge back on and and start it. Pressure came up within a few seconds, to my relief. I ran the engine for maybe ten minutes at around 1500 - 2500 rpm. Pressure looked good. I stopped and started a few times as the carby idle is too low. and it wants to stall. After it was up to temperature I let it rest while I read about how/where to adjust the carby. It's been on the dyno so I'm surprised it won't idle. Maybe they didn't adjust that.

 

I started it again and while I'm fiddling with the idle I see the pressure dropping. I give it a few more RPM but it keeps dropping. I shut it down, let it rest for half an hour, then poured more oil into the sender hole. Re-started but only 1 or 2 PSI pressure. I shut it down again. I think that there is a leak that's opening up when the engine gets hot.

 

The oil pump I'm using is a JP high volume pump. (The sump is a high capacity ASR sump.) I'm going to try a Holden oil pump from a 253 that my Dad has pulled apart. But it needs a good clean and once over.

 

To be continued. Thanks all for giving out your expertise!

 

 

 

[8BALL]

If the pick up has snapped just the "head" off it will still syphon but will cause issues when its running.
So could still be the pickup.
(If everything else checks out)

Hasn't spun a bearing has it?

[koalasprint]

Hi 8Ball, I think the main bearings would be OK. I checked the bearing crush and all were within spec. Not sure about cam bearings though. I'm hoping it is the pump as it's a far easier fix than anything else at this stage. But I honestly think it is probably the pickup. Maybe something stupid like a small piece of rag/cloth somehow left in the engine blocking things up.