[dannhepannhe]

Hello!
Im having some problems with my suburban 6.5 turbo diesel.
When the engine is warm my oilpressure is about:
2.8 psi @idle
34 psi @2000rpm
I know this is low.... but what is the limit for the engine to tanke no damage?
What should the pressure be and what could be the problem?
I have an external sensor and the original and Both says low pressure.
The dieselpump under the car is wired to the lights thats why i still can run the car i guess.

 

[OkDually]

Hello!
Im having some problems with my suburban 6.5 turbo diesel.
When the engine is warm my oilpressure is about:
2.8 psi @idle
34 psi @2000rpm
I know this is low.... but what is the limit for the engine to tanke no damage?
What should the pressure be and what could be the problem?
I have an external sensor and the original and Both says low pressure.
The dieselpump under the car is wired to the lights thats why i still can run the car i guess.

Try replacing the Oil Pressure Switch with AC Delco: D1808A
Your lift pump should not be wired to the lights to run.

The OPS supplies power to the lift pump for it to run correctly.
When the OPS goes bad the lift pump will not run correctly.
You will also get inaccurate oil pressure readings.

 

[Tommygunner]

Minimum oil pressures according to manuals for your engine. Is idle, 10 PSI, and 40 PSI at 2000 RPM. Low oil pressures like yours are usually caused by worn bearings in the engine. Did the low oil pressure happen suddenly. Or appear over time? What oil pressure connection did you install the second gauge or sensor to?

 

[dannhepannhe]

I allredy tried to replace the ops with a New one and the gauge were at the red part. I tried a external and i installed it in the hole the original ops is. Så i dont have the original inserted right now. I dont know when this happend because i bought the car over a year ago with other problems that i fixed and now when the car finally ran i saw this problem.... but i guess thats why somone wired the liftpump to the lights instead of the ops...

 

[OkDually]

I allredy tried to replace the ops with a New one and the gauge were at the red part.

If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part

 

[dannhepannhe]

If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part

It was the same as the old one at the gauge. 2 ops and 1 external shows low pressure so i guess it really is low pressure in the engine....

 

[Kgw51gmc]

If you use an aftermarket part you will get a false reading.
You must use the AC/Delco brand part

It was the same as the old one at the gauge. 2 ops and 1 external shows low pressure so i guess it really is low
pressure in the engine....

Time for a rebuild. But if it's a beater and no long term hopes, put 50 weight oil in it to boost pressure. Valves might starve for oil during startup, and maybe oil lines (Achilles heel with 6.5) will be under more stress, but if it's a rusted out, beat up rig you just need to run sometimes on the farm or similar situation, heavy oil. Or pull it and get check book ready, it's not cheap like rebuilding a 350 sbc

 

[dannhepannhe]

So the problem probably isnt the oilpump?

 

[jnlperformance]

Have you tried a mechanical gauge? Use a tee. Hook up a mechanical (10/15 bucks at any ole auto parts store) + standard ops (dually is right. Delco is the only one that will readout correctly - you're dealing with a 6.5 specific pcm so alot of the sensors are not universal like gasser stuff)

See what you're hitting on with a mechanical gauge.

Also... the oil pressure switch could be stuck open (maybe a chunk of rtv is lodged in switch... or debris of sorts??)

Tommygunner is correct. 10psi is absolute minimum but it should be around 25psi idle in optimal conditions. 40psi at 2k.

You start doing damage to the turbo impeller shaft and bearing races below 20psi.

:thumb: hope this helps.

 

[dannhepannhe]

But every sensor i tried showed a good pressure when the engine was cold and the it got lower and lower the warmer the engine got. if i got wrong sensor shouldnt it be wrong pressure even when cold?

 

[DieselPro]

Only option is to pull pan and replace oil pump and insert new rod and main bearings.

 

[dannhepannhe]

So can i do this with the engine in the car or do i have to lift it out?
What more than crankshaft main bearings and connecting rod bearings and oil pump should i buy? Like gaskets? I live in Sweden so dont wont to forget to buy anything lol.

 

[JMJNet]

Have you tried to replace the oil filter? last check and cheap.
I read some member with collapse oil filter and cause the oil pressure to be low.

 

[DieselPro]

Oil filter and thicker oil won't help. When the bearing clearances get to worn the oil once hot is too thin and the oil filter even if it was plugged solid would be bypassed by the bypass valve. So no easy fix. Might try the later style oil pump for the oil squirter type engine, maybe someone can show if indeed they do have larger oil pumping rotor. I have no experience in this so proceed on your own.

 

[DieselPro]

Might try > https://www.6-5liter.com/oil_pump.html

 

[JMJNet]

Have you tried to replace the oil filter? last check and cheap.
I read some member with collapse oil filter and cause the oil pressure to be low.

Clarifying my statement.

I am not saying that oil filter WILL solve the issue.
What I am saying is some people got a BAD oil filter which ended up to be collapsing internally that can cause low oil pressure.
Although, it is probably less than 1% chance but worth checking before tearing up the engine.

With part quality which is not very good nowadays, we need to check everything.

 

[tugboat94]

When I had the same issue on my 6.5 suburban. I removed the oil filter housing all together and replaced all the seals I think there was three total orings for the base, banjo bolt and one more.... I also swapped the oil cooler lines bc I was already there. I went from 10psi at 70mph on gauge to 65psi..... The oil filter relocation mod is one of the best imo wish I had done that

 

[Tommygunner]

One more thing to check.
Do the oil lines that go to the oil cooler appear to be new? Reason I ask this is. The person you bought the truck from may have had a oil line failure. This is a common problem with the original oil cooler lines. When they break, the engine instantly looses oil pressure. By the time the engine is stopped the damage to the bearings is done.
If the lines look like they may have been replaced. Then the old lines most likely broke, causing severe bearing damage which did not get repaired.
Also check the oil filter as said above. There are 2 oil bypass valves on the 6.5 engine. One is in the oil filter housing in case the oil filter gets blocked. The other is in the block to restrict flow of oil thru the cooler in cold temperature when the oil is thick, until the oil warms up. One of these bypasses may be stuck open causing a loss of pressure.
If it does turn out to be worn bearings. You also need to replace the camshaft bearings. They are usually the first to go bad in low or no oil pressure situation

 

[654L80]

You could try replacing the oil pump with one for a 1998. These pumps are higher flow because they had piston cooler jets. This will not fix the worn bearing issue but may be a cheap fix compared to rebuilding the engine.