North American Turbocoupe Organization



low oil pressure.....really low......
Noname
Guest
#1
I posted a couple days ago...but what happened was that I took a big valve head, hybrid turbo, front mount IC, ported lower intake, gutted upper intake and put it on my 88 TC. I got it all back together, but the damn thing is so noisy, more so with advanced timing. If you disconnect the SPOUT, the noise goes away a lot, but you can still hear it. I have it timed right, cam timing is right on the money. Ignition timing is 10. When I rev it up the engine sounds like a mechanical knock, like a rod knock or something. If you drive it....WHAT THE HELL IS THAT?!? that's what youd say. The noise is so harsh it rattles the car, seats, shifter, etc. I can't figure it out. Compression is about 135-140 on all cylinders. Fuel pressure is about 44 psi. Vacuum is about 10 inches at idle. It does have a big cam though, it has a Modern Performance .520 lift, that may be the cause of the knock. It has Modern Perf big valve head, stock shortblock 120k miles, T3/To4e 54 trim, Grand national intercooler, gutted upper, ported lower, removed EGR valve, tube, and solenoid, Bob big log header. The head, turbo cam directly off of my other car which ran GREAT with no problem at all (except ring blowby). My 88 TC had no engine problems at all before, never smoked, good compression. I put everything onto my 88 TC and now I'm having this knock problem. I also have VERY LOW OIL PRESSURE. When you start it up cold it idles at about 30-40 psi. As soon as it gets warm and you drive it a little, oil pressure goes down about 15-20. But....it also goes as low as 5 PSI!

Yesterday I tore apart the engine again to see what I could find. The head gasket was NOT on upside down. The oil pump pumps up pretty good I only have to turn the distributor gear a couple notches before it starts to spit oil. The pistons have a little play in them, but not much at all, not near as bad as my 86 TC which had blowby. The bottom end looks like its in good shape. I can't see any reason why the oil pressure would be so low. I did find some lifters that were wore, so I replaced all the lifters with ones from my old head, that got rid of some lifter taps I had, but the loud knock is still there. I have yet to look at the cam bearings, but other than that I can't find any reason why the oil pressure would be so low. What else could cause low oil pressure?

Even if the oil pressure is low for some reason, if I fixed that....I don't think it would cure the knock. Because even when I start the car cold, and its got like 40 psi oil pressure, It still knocks and shit. I don't know whether its a mechanical knock, or a spark knock. I ran codes and got nothing out of the ordinary....KS code and EGR. I swapped in different plugs/cap/rotor, no change. I can't find any noticeable vacuum leak...although I haven't did a carb spray check yet.

The only thing I did this time around was I put in the distributor from the 86 (it was a different part numer printed on the label on the distributor).

I've tried messing with the timing and backing it off to see if it goes away, the more retarded it is, the less you hear the noise, but even retarded way down to like TDC or lower than that, you still hear it LOUD and of course its still not driveable. The 86 does have a PE Computer, which my 88 does not. Other than that, there is no difference in anything else...besides the ACT sensor in the 88 harness.

Before I swapped heads, my 88 TC would get like 40 psi at idle, at WOT or revving it up, I would go to like 50 or so. I don't know whether its something in the head or not. The only other thing I did after replacing the head was changing the oil. I sprayed alot of carb spray onto the engine to clean out the head bolt holes and alot of it went into the oil probably. WHen I got it all back together I ran it like like that for about 20 minutes, then I changed the oil/filter, used 10w30 like normal.

What causes low oil pressure? What can I check, I need help because I'm running out of ideas.

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1988 TurboCoupe - 5 Speed - 115k miles - Fully Loaded except Leather
5"x8" K&N in fenderwell, SVO T3 watercooled .63/.60 A/R, Gillis Valve @ 18 psi, Gutted Upper Intake, Ported/Profiled Lower Intake, Cleaned/Flowmatched Stock Injectors, HKS Super Sequential BOV, Walbro 255 HP Fuel Pump, Kirban AFPR, Bob's Big Log Header, 3" DP, No Cat, Dual 2.5" UltraFlos into ATR SS axle/tailpipes, Centerforce Dual Friction Clutch, Pro 5.0 Shifter, Koni Adjustable Struts, KYB Gas-A-Just Rear Shocks and Quads, Custom Progressive Rate 1" Lowering Springs, M.M. C/C Plates, Energy Suspension Parts Everywhere, PST Ball Joints/Tie Rod Ends, Various Autometer Phantom Gauges
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Pete D Offline
Administrator
#2
With that high a lift cam did you check for clearance between the valves and the piston tops? Maybe this block was milled at sometime so you have less deck clearance. You can use a layer of clay on top of the pistons and turn it over by hand then check for valve imprints in the clay.

You say the noise gets less with the sprout out. tell us more

Was the head set up by somebody that know what needs to be done with high lift cams.
I don't remember the specifics but some machining work has to be done or the springs will bind. Don't know what binding springs sound like but.....
Check and see if any of the springs are cracked or broken.

Your oil pressure is getting too low when warm. Something is sloppy. Did you plastigage the clearances for the rods and main bearings? Looks don't always tell the story.
Did you take the pump apart and check clearances? Also check each piston by taking is very slightly past TDC, so it is just starting down. Then smack the top of it with the handle of hammer (wood) If it knocks it could be bearing or wrist pin hole problems.

Did any foriegn object get embedded in a piston top? BTDT


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NATO Member. it's not a vice, it's an obsession
Good judgement comes from bad experience, and a lot of that comes from bad judgment.
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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Noname
Guest
#3
Modern Performance did the head and cam so I don't know what they did. I bought a car that had this head already on it. The car it came off of ran great with no noises at all.

If I have the SPOUT in and rev it up, I can hear the noise CLEARLY, sounds like a growl or something. When I unplug the SPOUT, it seems to go away a lot, but you can still hear it, its just not that loud. This is the same with retarding cam timing, the more I retard timing, the less of the noise you hear.

I haven't plastigaged anything, I don't really have the garage to pull an engine out, or rip one apart.

I dunno what the hell is wrong here, I mean shit, the engine sounded fine before it was tore apart. I just threw these parts on, who knows what's wrong...
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Pete D Offline
Administrator
#4
You could let it idle and pull plug wires one by one and see if the noise changes. That might narrow it down to a specific cylinder

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NATO Member. it's not a vice, it's an obsession
Good judgement comes from bad experience, and a lot of that comes from bad judgment.
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm
Pete Dunham


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Jeff K Offline
Administrator
#5
Common cause of low oil pressure on these motors is excessive cam journal to cam bearing clearance.

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Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 20 psi, forced air intercooler, water injection, bypass valve, Ranger roller cam, subframes, etc., etc.. // 86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP nitrous, ignition, gears, suspension, etc., etc.... // 91 Escort: Bone stock winter car // 02 Taurus Vulcan(wifes car)
Jeff Korn

88 Turbo Coupe: Intake and exhaust mods, T3 turbo at 24 psi, forced air IC, water injection, BPV, Ranger cam, subframes, etc., etc.
86 Tbird 5.0 (original owner): intake, exhaust, valvetrain mods, 100 HP N2O, ignition, gears, suspension, etc., etc.
05 Taurus SEL Duratec daily driver
04 Taurus Duratec (wifes car)
02 Pontiac Grand Prix GT
95 Taurus GL Vulcan winter beater
67 Honda 450 Super Sport - completely customized
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Noname
Guest
#6
Thats what it was....I pulled the rockers out and the cam couldn't even spin by hand. I pulled out the cam and the bearings were so bad...they looked like they had threads in them... I got the new bearings in, polished up the cam journals and its going back in today
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Pete D Offline
Administrator
#7
Please, no offense meant but did you get the oil holes in the cam bearings lined up with the holes in the cam towers? I've seen heads that machine shops didn't line em up.
Pete Dunham


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