(very) HIGH oil pressure

wsp8 · wsp8's Garage

Installed the Pelican cam oil line restrictors while fixing all the many leaks on my '76 Targa and went from, maybe, 5 psi, to about 90 psi at cold start idle (1800 rpm). Is this normal?

What'll happen when I finally back it out and take it up to 65 mph ... blow the glass off the gauge?

I'm inclined to go back to stock. What do you think?

DonMo · DonMo's Garage

When the sender goes bad or is loose, it registers high or offscalel. Check your sender wire.

2.7RACER · 07-04-2006, 07:48 AM

What weight oil are you running? Going from a 50W to a 30W or even a 20W could help.
I would try removing one restrictor at a time to see what happens.
Re inspect both restictors for possible blockage and compare each passage for size. Also compare the restictors to the stock for size.
90 psi at even a fast idle, is too d*mn high. This is the summer time, what would it be in the winter?
Make sure oil is flowing to the cams, by careful inspection of the passage with a strong light.
If everything checks out for sure, I would consider enlarging the restrictor passage. Carefully, in small increments.
A hole 50% smaller than stock will flow 25% of stock.
I would not run this as is. 90psi is just too high.
My .02, soon to be obsolete, cents.

wsp8 · wsp8's Garage

Thanks for the advice! I'll check the wire. It's all been apart so that's certainly possible.

I put in 10W-30 to fire it up after a long hiatus, but will switch out as soon as it hits the road. Don't know if you've seen the restrictors, but they're at least 1/2 the diameter opening of stock.

How can you check for oil to the cams with a good light?

2.7RACER · 07-04-2006, 08:37 AM

wsp8,
I'm just saying with a strong light look for a possible blockage. I realize you won't see into a cam passage.
Hopefully, the wire is the problem. Although usually it just goes to the top and stays there, with a bad wire.
Good luck,

Chuck Moreland · 07-04-2006, 08:54 AM

Are you saying your pressure cold at 1800 rpm was only 5 psi?

That is much more worriesome than 90.

Cold oil pressure should be high, though 90 @1800 is a bit high. I would say the normal cold pressure @1800 is around 50-70 psi.

As soon as you get a little heat into the oil that will come down. Does the pressure get to normal range when at temp (aroun 1 bar/1000 rpm)?

That said, I am not a fan of the oil line restrictors.

Did you mess with the pressure regulator or relief pistons or springs?

wsp8 · wsp8's Garage

Sorry, as I remember during it's last outing last year (gettin' old), the WARM idle pressure was that low. I've read that's pretty typical what with all the leaks and such. BTW, the pressure on Saturday did drop to about 60 as it warmed up (before the fire started, anyway).

I DID replace both the prssure relief pistons and springs. I found one spring to be elongated past spec. Why?

wsp8 · wsp8's Garage

DonMO,

Are you referring to the sender next to the belt or the one behind the CIS stuff?

BTW, I'm a ' 79 VT grad (B. Arch.).

Chuck Moreland · 07-04-2006, 09:07 AM

Quote:

Originally posted by wsp8

I DID replace both the prssure relief pistons and springs. I found one spring to be elongated past spec. Why?

This is your problem. Get the right springs and pistons for your year car. They are not all the same.

Do not run the engine until you get this fixed. You run the risk of blowing up your oil cooler, that is an expensive mistake.

FYI, 5 psi hot idle pressure is not unusual.

wsp8 · wsp8's Garage

The new vs. old sure looked identical, except the length, of course

I certainly ordered them for my year. I know they are different if you have a remote cooler (I don't), but how else can I tell, then?

THANKS!

Chuck Moreland · 07-04-2006, 09:48 AM

Having a remote cooler has no bearing on the pressure spring selection. It is the on-engine cooler that you risk damaging.

Put your old springs back in (or new equivelant springs) and your problems will be solved. Be sure you use the matching pistons with those springs.

john walker's workshop · 07-04-2006, 09:58 AM

also the matching cap nuts. different depths.

Chuck Moreland · 07-04-2006, 12:20 PM

See this thread:
Need help. Too much oil pressure blowing up coolers

wsp8 · wsp8's Garage

Okay, thanks Chuck! I see that you've had personal experience with this. Fortunately, I didn't get to maximum (or beyond!) on the gauge. BTW, I was referring to the different types of pistons used depending upon the remote cooler, not the springs.

Anyway, I'll check the spring/piston assembly, but I really think I need to back off on those cam oil restrictors. After all, the car came with the slotted nuts and the new springs are slightly SHORTER than the originals, not longer.

Regardless, thanks for all the follow-up ... it's great to ponder these things with others!

Chuck Moreland · 07-04-2006, 01:43 PM

Know that a shorter coil spring is stiffer than a longer coil spring, all else being equal.

Again, I'm not a fan of the cam oil restrictor mod.

Mysterytrain · 07-05-2006, 06:18 AM

I had the restrictors installed in my 78 after the rebuild. I really got tired of the anxiety from watching the pressure gauge slamming the 5 bar and beyond mark for every cold start. I finally drilled the suckers out to 3.5 mm and everybody is happier for it.

wsp8 · wsp8's Garage

Thanks, MysteryTrain. That's just the kind of first-hand experience that I needed! I'm going back to stock tonight until I can have someone bore them out.

safe · safe's Garage

Quote:

Originally posted by Mysterytrain
I had the restrictors installed in my 78 after the rebuild. I really got tired of the anxiety from watching the pressure gauge slamming the 5 bar and beyond mark for every cold start. I finally drilled the suckers out to 3.5 mm and everybody is happier for it.

Did the drilled restrictors raise the hot pressure much?
How large is the unrestricted line?

mppickett · 07-05-2006, 06:31 PM

I installed the restrictors on my 82 3.3 930 rebuild and usually see 4 marks on the gauge (2-3 at idle). I never top out on the gauge (guess the bypass is working) and I've never see the gauge at 1 mark since the rebuild. I'm happy but it may not be for everyone.

wsp8 · wsp8's Garage

Okay, I now know 4/5 of the answers ...

a. seems SOMEONE (imagine some throat-clearing about now) forgot to torgue down the left cam line at the restrictor. Thus, every time that same SOMEONE circulated oil without ignition to keep things lubed, it seeped down the engine shroud and directly down into the HE.

Thus, the pooling, eventual smoke, then, fire!

b. the new pressure and safety springs are precisely the same as the ones I removed, so that wasn't the problem. (BTW, there's a good description of how/when they work in the Bentley manual).

c. The connection to the pressure gauge was also intact, so that wasn't it either.

d. HOWEVER, the switch back to the stock cam oil line adaptors resulted in a cold start of 60 psi ... right on the money. After a minute or two of warm-up it was dropping past 55. So ... the turbo restrictors are good for an increase of pressure, from 60 up to about 90 psi in my car.

e. what I don't know is what caused the smaller pooling in the right HE and resulting small(er) flames. Heaven forbid I blew the cooler with the high pressure.

I was so excited to be rid of the smoky smell with the new HEs and hoses. My plan (rather than remove the HEs) is to remove the hoses, flood the HEs with citrus cleaner and wipe them down very well with, maybe, a tube sock on a flexible stick of some sort. Any other ideas? Oh, and also to buy new paper hoses, again (!).