Turbo Carrera 3.2 (3.4) - losing hot idle oil pressure - which oil pump to use?

[Tippy]

Before I do a full teardown for the 3rd time, I want to make sure I covered all the bases on my low oil pressure situation.

Out of the blue, my 3.4 started getting warmer, quicker than before and the oil pressure has been showing lower than before.

Normally, it would be around 1.0 bar at hot idle.

All of a sudden, it has been getting down to 1.0 bar right when the oil temp gauge shows the motor is fully warmed.

Then, it drops even lower until maybe 0.5 bar or less at hot (below or near 9 o'clock oil temps).

I am swapping out both the oil pressure relief and safety springs soon (as the parts arrive from the host) and replacing the external T-stat cartridge albeit I have boiled water tested it.

The internal T-stat and external T-stat cartridges seemed to work fine, but replacing the external as one day, one of the pipes was ice cold and motor was pretty warm already.

With that said, if the oil pump is dying and is the root of the low pressure and warmer running conditions (less flow for cooling), what budget friendly pump should I run with a redline of 6750 and a turbo?

This time I will crossdrill the crank.

TIA

[Flat6pac]

I’ve installed a couple of GT three pumps this year there is modifications to the case
The problems we have with the Carrera oil pump and losing number two or number five rod bearing
That problem doesn’t exist in the turbos, you might consider a turbo pump.
Bruce

[Tippy]

Originally Posted by Flat6pac

I’ve installed a couple of GT three pumps this year there is modifications to the case
The problems we have with the Carrera oil pump and losing number two or number five rod bearing
That problem doesn’t exist in the turbos, you might consider a turbo pump.
Bruce

Thanks, Bruce.

Source for the pump?

[PeteKz]

Before you buy a new oil pump, or install new pressure springs, figure out why your oil pressure has suddenly decreased. Have you changed to a different, maybe lower viscosity oil? Are your OP sender and gauge operating correctly (put a direct reading analog gauge on the engine)? Did your operating RPM oil pressure decrease too? Is the oil pressure at operating RPM at least one bar per 1000 RPM? Did you reuse the old oil pump? If so, have you measured it for wear?

[Tippy]

Originally Posted by PeteKz

Before you buy a new oil pump, or install new pressure springs, figure out why your oil pressure has suddenly decreased. Have you changed to a different, maybe lower viscosity oil? Are your OP sender and gauge operating correctly (put a direct reading analog gauge on the engine)? Did your operating RPM oil pressure decrease too? Is the oil pressure at operating RPM at least one bar per 1000 RPM? Did you reuse the old oil pump? If so, have you measured it for wear?

I did have 10W-40 at first and of course went back to 10W-50 when this all started.

Yes, the sender was dying after confirming with a mechanical gauge. Replaced and saw another half bar at hot idle, but even now, it’s going lower.

Never touched the pump between all the rebuilds/refresh

[Tippy]

Originally Posted by PeteKz

Before you buy a new oil pump, or install new pressure springs, figure out why your oil pressure has suddenly decreased. Have you changed to a different, maybe lower viscosity oil? Are your OP sender and gauge operating correctly (put a direct reading analog gauge on the engine)? Did your operating RPM oil pressure decrease too? Is the oil pressure at operating RPM at least one bar per 1000 RPM? Did you reuse the old oil pump? If so, have you measured it for wear?

Oil pressure at hot idle (900-950 RPM, 9 oclock) is like 0.2-4 bar.

But, it will jump up quickly with a little RPM and still hit well over 3 bar by higher RPM at these temps.

[85RedCarrera]

If you have sufficient oil pressure at higher rpm’s, isit possible that one of more of your piston squirters are stuck open at idle?

[stownsen914]

Interesting point about a squirter sticking open. Squirters do fail.
People talk a lot about the cam oil restrictors to improve idle oil pressure. No specific advice to offer, but it might be worth looking into if you're not using them.

[Magyar Kiwi]

Hi
As a Porsche oil pump, (in good order) is a constant displacement pump, oil pressure is a function of RPM & oil viscosity and how much oil is escaping/leaking from the system, through relief valves, bearing clearances, piston squirters and tensioner bleeds etc.
If you fit a new oil pump with the same size pressure section, it may well not fix your low pressure at idle problem.
Suggest you focus on determining where the excess system oil leakage is occurring.
Are you using the the oil restrictors that screw into the cam boxes ?
Has the oil relief valve on the top of one of the chain tensioners failed/popped off ?
Hope this helps.
Cheers

[mikedsilva]

Originally Posted by Tippy

Before I do a full teardown for the 3rd time, I want to make sure I covered all the bases on my low oil pressure situation.

Out of the blue, my 3.4 started getting warmer, quicker than before and the oil pressure has been showing lower than before.

Normally, it would be around 1.0 bar at hot idle.

All of a sudden, it has been getting down to 1.0 bar right when the oil temp gauge shows the motor is fully warmed.

Then, it drops even lower until maybe 0.5 bar or less at hot (below or near 9 o'clock oil temps).

I am swapping out both the oil pressure relief and safety springs soon (as the parts arrive from the host) and replacing the external T-stat cartridge albeit I have boiled water tested it.

The internal T-stat and external T-stat cartridges seemed to work fine, but replacing the external as one day, one of the pipes was ice cold and motor was pretty warm already.

With that said, if the oil pump is dying and is the root of the low pressure and warmer running conditions (less flow for cooling), what budget friendly pump should I run with a redline of 6750 and a turbo?

This time I will crossdrill the crank.

TIA

I'm no expert as everyone knows, but will share a similar (not identical) experience.
An early engine I had was showing lower than desirable pressure at idle. But when revving above idle, it had normal pressure according to the gauge.. ie, 1 Bar for every 1000 rpm..

However I pulled it apart and found that the main tunnels in the case were oversize quite a lot. Which basically meant I had several 'small oil leaks'... the case was resized, NEW BEARINGS WERE INSTALLED, and that engine now shows 1.5B at hot idle.

I don't think that rebuilding it was totally necessary but I wanted to learn more about these engines.

Not saying you have the same issue, (it might be rods also) and I hope this is not your issue.

[Tippy]

Originally Posted by 85RedCarrera

If you have sufficient oil pressure at higher rpm’s, isit possible that one of more of your piston squirters are stuck open at idle?

I will definitely look during teardown.

[Tippy]

Originally Posted by Magyar Kiwi

Hi
As a Porsche oil pump, (in good order) is a constant displacement pump, oil pressure is a function of RPM & oil viscosity and how much oil is escaping/leaking from the system, through relief valves, bearing clearances, piston squirters and tensioner bleeds etc.
If you fit a new oil pump with the same size pressure section, it may well not fix your low pressure at idle problem.
Suggest you focus on determining where the excess system oil leakage is occurring.
Are you using the the oil restrictors that screw into the cam boxes ?
Has the oil relief valve on the top of one of the chain tensioners failed/popped off ?
Hope this helps.
Cheers

You know, I am pretty sure I have the restrictor style adapters, but I need to check again.

I need to reword the beginning. I did not tear 3 times in a row because of a low oil pressure situation, was simply stating I am going into this motor for the 3rd time in 18 years and never touched the oil pump.

It is simply wearing out if I had to guess.

[Tippy]

Originally Posted by mikedsilva

I'm no expert as everyone knows, but will share a similar (not identical) experience.
An early engine I had was showing lower than desirable pressure at idle. But when revving above idle, it had normal pressure according to the gauge.. ie, 1 Bar for every 1000 rpm..

However I pulled it apart and found that the main tunnels in the case were oversize quite a lot. Which basically meant I had several 'small oil leaks'... the case was resized, NEW BEARINGS WERE INSTALLED, and that engine now shows 1.5B at hot idle.

I don't think that rebuilding it was totally necessary but I wanted to learn more about these engines.

Not saying you have the same issue, (it might be rods also) and I hope this is not your issue.

The bearings snapped into place during replacement this last time, the case journals should be fine.

The crank journals have been nominal the other 2 times.