Oil pressure under load.

[Brigsy]

Since fitting the new cam in the van ive noticed the oil pressure is dropping when the engine is loaded up or at wot. Im taking the reading from above the one way valve on the turbo oil feed.

Before fitting cam i had 60lb oil pressure cold. 42ish lb warm 2k & above. This was with semi synthetic comma 10/40. The reading used to drop slightly to 38/40 on wot.


Now after fitting new cam i have 50lb cold. 40lb hot 2.5k onwards.

The problem is now when on wot the oil pressure drops to 35lb but if you lift off it will hit 40lb again. The only difference is im using mobil super s 10/40 semi synthetic & different cam.

The question is this down to new cam, i.e different tolerances in cam bearings

Is the bottom end showing signs of wear (still sounds sweet as a nut)

Oil pump worn? prv fault?

Oil too hot? i have no means of checking this as yet.

Or is this a case of 'c1j' paranoia? Im concerned as i dont want to be shafting turbos every other week.

[Mart]

2 thoughts...

Could be shady tolerances on the cam bearings.

Or, perhaps where the ambient air temperature has increased now we're out of Winter, the radiator isn't as efficient at cooling/cooling the oil circuit, hence the oil is getting slightly more hot, and thus then slightly thinning more, hence the drop in pressure.

All of this is assuming your oil pressure gauge/sensor is sweet as.

Personally, I've always aimed for 45psi oil pressure as a minimum @ the turbo, so yeah, I'd be a wee bit concerned seeing 35psi.

As a cheaper 'test', you could try filling up with the oil you used to run, and see if that helps matters. If it does, you know then to avoid Mobil's oils. If it doesn't, hook up a suitable probe & and measure the oil circuit temp's.

[Sparkie]

id be running a large oil cooler if i were you. and maybe 15w50 or 10w60 oil as they handle high temps better....

[Brigsy]

Im using a racetech mechanical gauge to monitor oil pressure.

I might whip sump off, Refurb the pump & get a temp probe fitted whilst on with it. Cheapest option first

With the added size/drag of the van do you think an external oil cooler is needed? Ive got a mocal setup here but it has a shady small cooler, 7 row possibly. Could get a cooler & whack that on if needs be. What size oil cooler would i go for, as i have no idea what is needed.

[Jono]

I have an mechanical oil pressure guage after the one way valve and an oil temp guage. I also run Fully synthetic 10w60 oil.

The temperature of the oil makes a huge difference to the oil pressure maybe as much as 8psi over 75-95 degree spread. I see "around" 42psi at 80 degrees though it does seem to vary a couple of psi. I dont run an external oil cooler but I am considering it as on the motorway the oil temp slowly climbs. Where as the water temp stays constant.

What is the optimum oil temp I always assumed around 80 for the C1J.?

[Brigsy]

Removed the one way valve out of the turbo oil feed today to see if it made a difference as i had turbo oil feed off. I now have between 42-45lb when hot cruising. Idle is up to 15lb. On wot/high load the pressure is still dropping down to 38lb.

Is the one way valve really needed. I watched my pressure gauge on start up & the pressure built up as normal....

Got oil pump refurb kit on order, Going to change oil/filter too. My local motorfactors sells millers motorsport 10/60 fully synth, should i give this a go. Also treated myself to an expensive racetech duel oil pressure/temp gauge today so will hook that up.

On the downside i got the old blue smoke on idle tonight, that'll be the turbo on its way out then

[Scoff]

I used to have a strange oil pressure reading with my old rear engine C1J, it would read higher pressure while cruising or on overrun but would drop maybe 5psi when accelerating, even if only moderate acceleration. I don't know what caused the difference, it was regardless of rpm. something, be it a tolerance somewhere must be changing between load and no load. I thought maybe big end shells. I couldn't think of anything else.

[Brigsy]

Thats the exact problem i have Scoff. Could be big ends, seems weird as it runs/sounds really nice.

Will i get away with taking a cap off one at a time to inspect whilst sump is off?

[Sparkie]

funnily enough i have exactly the same problem with the turbo 2.
engine is sweet, cruising, the oil pressure is good.
accelerate sharply and for a long period the pressure drops.
i always assumed the oil got hot, gets thinner and the pressure drops off.

he millers oil if pretty good. - give it a go and change the filter too. i bet the pressure goes up.

[Matt Cole]

I may stand corrected here, but i tried a lot of oils over time and that mobil super s for the price beat it all hands down!! I was seeing over 100 deg temps at cadwell and still maintained above 40 psi oil pressure. Ive had some oils get way too thin and shat out of the exhaust at high rpm. Brigsy if pressure drops at high revs then flow will too. Doesnt sound like a blockage as the pressure is good at low rpm. The higher the revs the higher the flow and pressure needed. Could be the pump tolerances not close enough as and when the oils viscosity changes with temp.

[jantheeven]

I may stand corrected here, but i tried a lot of oils over time and that mobil super s for the price beat it all hands down!! I was seeing over 100 deg temps at cadwell and still maintained above 40 psi oil pressure. Ive had some oils get way too thin and shat out of the exhaust at high rpm. Brigsy if pressure drops at high revs then flow will too. Doesnt sound like a blockage as the pressure is good at low rpm. The higher the revs the higher the flow and pressure needed. Could be the pump tolerances not close enough as and when the oils viscosity changes with temp.

I run some cheap brand 10W40 semi-synthetic oil and my oil pressure is also between 40-43 psi while oil temp is 100... so I'd have to agree with this possibility...

[Brigsy]

Had it in bits today & the pump internals are worn & scored. Fingers crossed the new pump internals will cure the problem. Had a right carry on removing/refitting the baffled sump in situ, A job i don't want to do again in a hurry. Had to jack the engine up.

[jantheeven]

Had it in bits today & the pump internals are worn & scored. Fingers crossed the new pump internals will cure the problem. Had a right carry on removing/refitting the baffled sump in situ, A job i don't want to do again in a hurry. Had to jack the engine up.

I hear ya... it's a nasty job... been there, done that, have the t-shirt...

[Matt Cole]

Somebody mocked me the other day for suggesting removing the lump to seal a leaking sump and timing chain cover!! Its a ******* of a job to do in situ if you want to to it correctly, leak and hassle free!!

[Matt Cole]

I would check the caps too mate, whats damaged one, may have damaged the other

[Brigsy]

Too late its all back together now. Will see what the score is tomorrow when i refill with oil.

[djinuk]

After spending the last to days fukin about with the timing cover and the sump i 100% agree , its not a crazy idea whipping the lump out.. but then again my car is a dog and everything is bodged.

[Ashy]

Somebody mocked me the other day for suggesting removing the lump to seal a leaking sump and timing chain cover!!

Noooo Who was it???

[djinuk]

out of interest would an oil leak outa the timing chain cover (around the edge) affect oil pressure.

[Matt Cole]

Noooo Who was it???

They know who they are!!

[Matt Cole]

Whats the result then briggsy? All sorted?

[Brigsy]

Sorted. 65lb cold, 22lb idle & 48lb 2k hot. Holds over 45 psi at any revs now.

Im assuming the new pump internals are doing the business, Have changed the oil to 10/60 fully synth so this has probably helped. Lets hope the turbo doesn't give in now eh.

[Scoff]

10/60 for me used to give me about 3psi more than 10/50 on average when hot I remember, I guess the rest will be your pump

[Brigsy]

Ive also shimmed the prv up by 1mm too, whether it makes a difference who knows.

[Scoff]

Ive also shimmed the prv up by 1mm too, whether it makes a difference who knows.

That used to make more difference when cold when I did it. I ran about 2mm shim, didn't make much odds once it was warm to be honest