Oil Pressure Questions

[88F350idi]

Hey all,
i've got an 88 with a 94 7.3 idi non turbo and i added a factory turbo a while ago. the turbo died about a month ago (which wasn't a big surprise). the shaft bent and was pretty screwed. I had a good spare in working condition that i took in for a rebuild and balancing. while the work was getting done on the turbo i took the opportunity to replace my head gaskets and head bolts and also did a smf conversion. with the new turbo bolted on my, oil pressure is significantly lower than before. at hot idle i'm seeing 9-10 psi. I have an autometer mechanical gauge. i tried another mechanical gauge with the same results. tried swapping out the psd oil filter for the smaller idi filter. same. I found specs everywhere that say pressure at 3300 rpm should be 40-70 psi and i'm not seeing that when it's revved up. also when i start the engine the pressure builds very slowly instead of shooting up like before. highway at 105 km/h (about 65 mph) pressure is around 20-25 psi. I'm going to try swapping oil pump and see how it goes. Any ideas would be great...

 

[jonathan]

it could be the rear header on the oil cooler

 

[88F350idi]

it could be the rear header on the oil cooler

could you elaborate on that a little?

 

[jonathan]

there is a presure spring in there that gets worn out sometimes

 

[OLDBULL8]

Stop and think about it, a small or large filter has nothing to do about oil pressure, they are full of oil all the time. Pull the filter off and see if the bypass valve is stuck open, or maybe something is caught in it holding it open, like a piece of silicone. Bypass valve is the little round circle off to the side spring loaded, you can push it in with a screwdriver or something. This is off a 90 but yours is similar.

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[Silver Burner]

there is a presure spring in there that gets worn out sometimes

Where is this at on the motor?

 

[OLDBULL8]

Stop and think about it, a small or large filter has nothing to do about oil pressure, they are full of oil all the time. Pull the filter off and see if the bypass valve is stuck open, or maybe something is caught in it holding it open, like a piece of silicone. Bypass valve is the little round circle off to the side spring loaded, you can push it in with a screwdriver or something. This is off a 90 but yours is similar.

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Where is this at on the motor?

Read and look.

 

[Diesel JD]

It's right where the oil filter threads on to the oil cooler bundle. I do wonder if you have the oil pressure sender in the stock location if having a healthy turbo isn't doing it's typical thing and being a high oil use item, therefore the pressure there is less. Ignore this if you have the sender at one of the other ports down low. If 25psi is a true reading it is not quite enough, close but it should do better. On the early 6.9s the minimum spec was 30 psi hot 2000 rpm and up and then in 86 or 87 they changed it to 40 minimum without any real changes to the crankshaft or bearings, ever in the IDI run really except the larger wrist pins and bosses on the C and K code turbo engines, therefore I personally would feel ok with any oil pressure over 30 with the engine warmed up, 2000 rpm and over and over about 5-7 hot idle. More is better as long as it isn't extreme though.

 

[88F350idi]

Thanks for all the input everyone. i will do a little work on it tomorrow and see what i come up with.

 

[icanfixall]

The spring is part of the oil pressure regulation valve. Its stacked in the rear oil cooler header. The only way you can get at it is to remove the rear cooler header so... If your planning to replace the oil pump take this apart first when the engine is out of the rig. You cannot do this oil pump with the engine in the rig. Just not enought room to work and our joints don't bend thay way. We only have 4 bolts on the motor mounts... another 6 around the tran. autos have 4 holding the torque converter and 4 exhaust bolts or nuts... Not that much real work pulling an engine.... Just need a cherry picker able to handle 2000 lbs and an engine stand able to hold at least 2000 lbs because of the hanging weight....

 

[phazertwo]

I have a similar issue, but I only have the factory OP gauge to go off of (which is crap), and I blamed the gauge.

Sometime the gauge reads almost stright up and down (just ever so slightly twords the N) other times it reads below the N. It is eaiter one or the other. It will change while on a long drive (and I can hear/feel/see no difference in how the truck runs) but I never actully see it happen. I am wondering if I have a OP problem, and plan on installing a gauge very soo to make damn sure that my engine is getting enough pressure.

PZ

 

[88F350idi]

The spring is part of the oil pressure regulation valve. Its stacked in the rear oil cooler header. The only way you can get at it is to remove the rear cooler header so... If your planning to replace the oil pump take this apart first when the engine is out of the rig. You cannot do this oil pump with the engine in the rig. Just not enought room to work and our joints don't bend thay way. We only have 4 bolts on the motor mounts... another 6 around the tran. autos have 4 holding the torque converter and 4 exhaust bolts or nuts... Not that much real work pulling an engine.... Just need a cherry picker able to handle 2000 lbs and an engine stand able to hold at least 2000 lbs because of the hanging weight....

Thanks. i am quite familiar with the procedure i had it out a week or two ago...

 

[Black dawg]

the reference pic isnt showing the spring that controls oil pressure, only filter bypass.

 

[OLDBULL8]

the referense pic isnt showing the spring that controls oil pressure, only filter bypass.

Can't see it eh! Well the damn spring is in behind the little disc. In order to see the spring you have to grind the little stacked tabs off then it will pop out at you. It's a pressure bypass valve if the filter gets plugged up. The oil pressure control is built into the oil pump.

 

[poolguy]

I had the same thing happen when I replaced my turbo! I read my oil pressure at the turbo.
Been driving it that way for over 2 years, nothing has changed, no worse no better. So I guess it's ok!?!?
Dunno!?!?

Chuck