Jackfit

Morning Ladies and Gentlemen,

Continuing with the oil pressure problem on the L79 (66) . While waiting to install new oil pump, screen ( taking drugs to relieve anxiety ) and not having a gauge to test ring seal, ( coming soon thanks to Blockman ) I did a compression test on all cylinders this morning ( with pants on )

Rebuilt engine now has 325 miles on it

Results lbs

#7 185 # 2 185
5 180 4 190
3 182 6 171
1 175 8 185

Question remains on dark oil after start up and filter change (twice)

Just to keep members updated and for other suggestions

Jack

Ron Miller

Jack,

My thoughts, as from beginning,

1. I'm thinking that you'll see some improvement in oil pressure with the new oil pump.

2. I'm thinking your dark oil is from the engine setting for an extended period of time with the assembly lube inside, who knows what that was. But, I don't think it'll prove to be a problem.

3. Your cylinder pressures don't appear to me to be out of line.

4. Keep your chin up and your pants on, buddy!!

Ron

MikeM

You dark oil if from the assembly lube. Not from blowby. Nothing wrong with your cylinder readings.

I still think you have a plugged pump screen but somebody brought up a good possibility in your other thread. The relief valve could be stuck in your old oil pump which will also give you exactly the symptoms you have.

Frankie the Fink

Maybe between all the old lube and a sub-par oil pump that would explain the pressure fluctuations....somebody prob already mentioned it but the pump pick up height in relation to the bottom of the pan is critical....so check the new one out carefully. Somebody smarter than me (MikeM?) on the topic may be able to provide more detail....

Jackfit

I think you all have too much time on your hands to be replying so fast to my posts.

Get a job or go for a ride, I would but the dam rain won't stop here in Maine, I don't have soft top on, but the sun looks like it may come out and what the hell,

15 pounds at 50 mph should be Ok

Jack

Ron Miller

Too much time is what comes with retirement and only working part time, but I'm luvin' it!!!

And, part-time for me is just about right, especially when I get to pick and choose which part of the country (or overseas, now and then), I'm going to. And when it's a good location, the wife can travel along and we turn it into a vacation when the work's done.

I'm goin' for a ride in a couple of days, as soon as I get my new wheel bearing returned from Van Steel, coming tomorrow. ('Till then I'll drive the '65 coupe, although summertime is on the way in southeast Missouri, gotta get the top down on the '66!!)

This retirement is pretty damn great, like McDonald's, "I'm luvin' it!!"

Frankie the Fink

Right on! I sit around my pool in FLA - gaze at the lake and work part time in my bathing suit... It was a long road and me and the 'ole lady started out 40 years ago without a pot to whiz in... Not Bill Gates but I do pretty much what I want every day..

Jackfit

You know even when my car was my main means of transportation 40 years ago, it seemed like I was always putting in a starter, alternator and some other part. I have thrown out more original parts ... or we handed them in to car parts stores for a " new rebuilt " one. Back then, I just had to use a curb for a jack to get under the car. (corvette jacks - not safe) Not much room in NYC at the time. But we love um

Can I go on your next vacation?

I did go for ride, just used an umbrella to keep rain off head.....

Jack

AZDoug

About 30 years ago, once I stopped putting in rebuilt parts and bought new, my problems stopped.

Doug

66L72

I am not sure how your oil pick up is secured to the oil pump. Mine is a press fit and when installing the pan the engine builder must have bumped the pick up causing it to not be aligned flat to the bottom of the oil pan.

i now know that it is good practice to secure the pick up in position to the pump with a bit of weld.
it was very expensive for me to learn what my builder or his apprentice should have known........

Mossy66

Bring pants

Ron Miller

Dennis Beck

I think when this thread started you said this was a fresh rebuild. Were the cam bearings replaced? This could cause low pressure if they were not replaced.

Dennis

Jackfit

I want to say yes, but I am looking for the paper work. The motor was rebuilt 4 years ago and sat on my engine stand till this fall. subjected to below 0 temps in winter. I believe the cam , lifters , valves , stems , rockers , rods, push rods, pistons, rings etc, were replaced. The crank was turned. I had lost the original heads in 1972, and the rebuilder located 202 (1965) heads to replace the small valve heads that a rebuilder had put on in 1982.

I will have the pan off soon and we all hope it is just a clogged screen and the original pump, with a bad valve spring . The car has always had lowish pressure.

Jack

jim lockwood

While you have the pan off, consider also removing the rear main bearing cap.

With the cap off, you will be able to see into the oil passage leading from the pump to the filter. About an inch into this passage there should be a small Welch plug that separates this passage into "pre-filtered" and "post-filtered" sections.

If this Welch plug has slipped out of position, it could be partially blocking the oil path to the filter. Depending on how far out of position it is, there could be a dramatic effect on oil pressure.

FYI: There are some who believe that if this plug is missing entirely there will be an effect on oil pressure. I don't buy that since all its absence would do is to create a bypass path around the filter.

Jim

buns

I personally don't know, but according to John Lingenfelter: "If the plug is missing the engine will lose as much as 20 psi because oil is leaking past this plug before reaching the rest of the engine. Idle oil pressure will be especially low. The missing plug can be mis-diagnosed as a weak oil pump, excessive clearances or any number of problems that will defy repair."

67pete

My 67 L79, when new, had 205 - 210 lbs of pressure.

BLOCKMAN

That is total BS as all it does is bypass the filter once its full of oil as the oil is going to go to the path of least resistance.

BLOCKMAN

I would have to disagree with you on this one as the compression test was fine but leak down test at TDC proved what I was saying in his other post the dark oil with that little miles is do to poor ring seal.

This is a qoute from the other thread as you can see the best leak down was 8% and the worst was around 35% and I would say the average was around 18% and on a newly rebuilt engine thats below standard. It was pushing air out of the crank case breather behind the intake manifold.

This is not the first engine I have seen where substandard work was done and only a leak down test will tell if you have good ring seal at TDC.

BLOCKMAN

I can see by the pics that the bearing wear is not centered and most of the wear is on side of the bearing, Thats why I am a big advocate of line honing every block we go through as it also shows taper on the crank journal but where it was turned I would have to say the housing bore is tapered not the crank.