mikestertwo
Well-Known Member
- Joined
- Sep 13, 2006
I know this has been beat to death but make sure the rear cam bearing is installed correctly. Take the rear cam plug out and make sure the bearing is covering the oil feed hole.
engine is out.......again......
- Thread starter Blazer406
- Start date
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
Is this a factory or aftermarket timing cover? If aftermarket, check for cracks. If it is factory, check for cracks. So, check the timing cover for cracks.
I only radius oil passages in the timing cover, but not enlarge them. The stock timing cover will feed enough oil for a 600hp engine. I am just jealous about making things better, so I radius all the passages and then spend copious amounts of time setting the oil pump clearances. It sounds like there is a timing cover issue to me, though. You might just want to try another one to rule that out.
I don't think that a .020" bigger cam bearing would restrict oil flow to that main bearing significantly. It is only .010" farther into the oil gallery that is already HUGE.
edit: Also check the oil pressure relief valve for smooth operation. Also check the oilfilter adaptor for cracks, too.
I only radius oil passages in the timing cover, but not enlarge them. The stock timing cover will feed enough oil for a 600hp engine. I am just jealous about making things better, so I radius all the passages and then spend copious amounts of time setting the oil pump clearances. It sounds like there is a timing cover issue to me, though. You might just want to try another one to rule that out.I don't think that a .020" bigger cam bearing would restrict oil flow to that main bearing significantly. It is only .010" farther into the oil gallery that is already HUGE.
edit: Also check the oil pressure relief valve for smooth operation. Also check the oilfilter adaptor for cracks, too.
Once upon a time I checked for internal oil leaks with a garden hose. Engine on the stand, front cover off, garden hose hooked up to the oil pressure sender port. I was taking the thing to the machine shop anyway, so I didn't feel bad about it. I did have to figure out ways to cover up a few other holes before I did this. In the end it was quite informative - I found my major leakage was between the #1 cam journal and bearing. The wear didn't look that bad to my eye, but the water flowing out from there didn't lie. You could do something similar. If there is a crack or something somewhere, it would show up with this kind of test. Gotta do the suction passage separately.
Another guy here in Houston did something similar, except he had his machinist set up the test and use a light oil instead of water. They found a major leak between the block and the #1 cam bearing. The hole in the block was apparently out of round, or distorted in some way. He lost 3 rebuilds because of it. They had to hone that hole out and use an oversized bearing, but once they did that his engine finally lasted and kept good oil pressure.
I think a similar test might help you find your problem. Maybe use a light oil, and pressure it into the engine with an air compressor, so you don't foul everything up and require a complete disassembly and cleaning. Since you have good pressure cold but poor hot, I'm guessing that it is a small leak somewhere that doesn't become bad until the oil thins out. Once the oil gets thin, then enough escapes through the leak to drop the pressure.
John
Another guy here in Houston did something similar, except he had his machinist set up the test and use a light oil instead of water. They found a major leak between the block and the #1 cam bearing. The hole in the block was apparently out of round, or distorted in some way. He lost 3 rebuilds because of it. They had to hone that hole out and use an oversized bearing, but once they did that his engine finally lasted and kept good oil pressure.
I think a similar test might help you find your problem. Maybe use a light oil, and pressure it into the engine with an air compressor, so you don't foul everything up and require a complete disassembly and cleaning. Since you have good pressure cold but poor hot, I'm guessing that it is a small leak somewhere that doesn't become bad until the oil thins out. Once the oil gets thin, then enough escapes through the leak to drop the pressure.
John
Is this a factory or aftermarket timing cover? If aftermarket, check for cracks. If it is factory, check for cracks. So, check the timing cover for cracks.
It is the stock cover that came off my '87 GN. Will definately check for cracks.
Trying to buy one or two used ones here on the board. I was thinking the same thing..... just build another one up.... and try it..... to eliminate that as being an issue.
I have checked the oil pressure relief in the filter housing.... it appears to be operating smoothly.... and functioning properly.
Thanks for the tips. I am definately open to any fresh ideas.
Excellent idea. I have thought about the light oil idea.... even to the point where I was trying to find a viscosity comparison chart for engine oils at different temps. I wanted to pick an oil that at room temp would be as thin or thinner than 10w30 or 10w40 at say 225 deg. I would guess water would be plenty thin.
My hope is that it would be obvious where "the leak" is when you do that test. What I am afraid of.... is not being able to tell definitavely where is the issue is..... although the pressureized water deal should do it.....
Thanks for the tip.
Unfortunately I haven't had time to even pull the intake off to check anything since geting the motor out..... maybe this week sometime I can get a good look at it.
I'm trying to think of an inexpensive light oil... I dunno. How about a few gallons of diesel? It should be plenty thin, you can flush it out easily with motor oil, it's cheap and easy to find, and you shouldn't have any worries about blowing yourself up with it
John
John
turbofabricator
Well-Known Member
- Joined
- Mar 7, 2004
Even just blowing compressed air through the oil gallery will point out the major leak points. Take a rubber tipped air nozzle and shoot it into the front oil gallery with the timeing cover off and averything else installed. Listen for a major air leak and go from there.
Sounds like my luck
I built a 350 for first time, put in a comp cam and tried to save some money on lifters. Motor sounded awesome and broke in well, then cheaper lifters went flat making me a nice paperweight. Not same as your issue... but just saying. Maybe, if it is a crack causing a pressure loss its not visible or open until block gets to operating temp causing it to loose oil in it. I hope you resolve it though b/c I know it really stinks to pull , and reinstall. Would be worth chasing all oil galleys and putting pressurized oil through. Good luck and let us know so us newbies to the 109's may can avoid the same.
I built a 350 for first time, put in a comp cam and tried to save some money on lifters. Motor sounded awesome and broke in well, then cheaper lifters went flat making me a nice paperweight. Not same as your issue... but just saying. Maybe, if it is a crack causing a pressure loss its not visible or open until block gets to operating temp causing it to loose oil in it. I hope you resolve it though b/c I know it really stinks to pull , and reinstall. Would be worth chasing all oil galleys and putting pressurized oil through. Good luck and let us know so us newbies to the 109's may can avoid the same.
Haven't made any progress in the past week or so..... engine is still on the stand waiting on me..... been juggling a 4 month old... a 7 year old...that is just now wrapping up baseball.....full time job......full time wife.....etc. etc..... I know... all excuses......
Hopefully soon I will make some new headway and give you guys something to think about and give me some more suggestions......
Hopefully soon I will make some new headway and give you guys something to think about and give me some more suggestions......
As a matter of fact, I did Bob. Can't remember all the details I put in this thread.... and I am too lazy to reread it tonight.
When I first built the motor, all the machine work was done fresh. I had the whole ball of wax done. Cleaned, degreased, shot blasted, line bore/hone after steel caps installed, decked, bored, new freeze plugs and new cam bearings.
Looking back, it makes sense. Apparently there was a burr or something on the #2 cam bearing. The cam somehow grabbed the bearing and it spun the very first time I hit the starter after the rebuild. I remember the motor spinning over and it stopped suddenly and almost kicked back like the timing was off. That is when it spun the bearing.
I found this after a couple times out and on the stand. I thought my rod and main clearance was a little on the loose side.
Anyway, when I figured it out, my machinist said he could bore the #2 journal out and install a #1or #4 bearing in there because they are slightly larger OD. He doesn't have a line boring machine for the cam. Back in the car.... still poor oil pressure after she gets hot.
After narrowing everything else out, I knew it had to be the cam journal problem child. I ended up selling that entire long block to a friend and told him to take it to someone who could line bore the cam journals and install oversize cam bearings. He did. Upon reassembly and installing this motor in a different GN, oil pressure is awesome all the time. 200 deg engine and it has 50 psi oil pressure with reasonable oil. Motor has been fine ever since.
I might get this motor back at some point.
There is the latest.
When I first built the motor, all the machine work was done fresh. I had the whole ball of wax done. Cleaned, degreased, shot blasted, line bore/hone after steel caps installed, decked, bored, new freeze plugs and new cam bearings.
Looking back, it makes sense. Apparently there was a burr or something on the #2 cam bearing. The cam somehow grabbed the bearing and it spun the very first time I hit the starter after the rebuild. I remember the motor spinning over and it stopped suddenly and almost kicked back like the timing was off. That is when it spun the bearing.
I found this after a couple times out and on the stand. I thought my rod and main clearance was a little on the loose side.
Anyway, when I figured it out, my machinist said he could bore the #2 journal out and install a #1or #4 bearing in there because they are slightly larger OD. He doesn't have a line boring machine for the cam. Back in the car.... still poor oil pressure after she gets hot.
After narrowing everything else out, I knew it had to be the cam journal problem child. I ended up selling that entire long block to a friend and told him to take it to someone who could line bore the cam journals and install oversize cam bearings. He did. Upon reassembly and installing this motor in a different GN, oil pressure is awesome all the time. 200 deg engine and it has 50 psi oil pressure with reasonable oil. Motor has been fine ever since.
I might get this motor back at some point.
There is the latest.
- Joined
- Feb 18, 2006
Hmm. So the cam bearing was turned blocking the oil hole? How would that lower oil pressure??
No, when my machinist bored out the #2 cam journal hole to accept the oversize bearing, all 4 cam journal holes were no longer in a line....and apparently #2 was egg shaped a little. Later, when the machine shop that eventually removed those cam bearings to line bore the cam journals discovered the cam was not even touching on a good portion of the bearing in #2 hole and that excess oil clearance was making oil bleed out bad and cause me to have poor oil pressure when the oil got hot and all the clearances grew.
The new line bore and 4 fresh cam bearings all in the same line fixed the oil pressure issue.
The new line bore and 4 fresh cam bearings all in the same line fixed the oil pressure issue.
Pronto
Believe nothing you hear and half of what you see.
- Joined
- Dec 9, 2002
Well, if you know the issue involved the cam bearings and alinement, why didn't you get that fixed? I am assuming the rest of the build was fine. Did you just get frustrated with the whole thing and not want to look at it anymore?
Exactly.
I ended up with a stroker motor with GN1 heads instead and a girdle. So I upgraded while I had the chance.
X2 I had a guy cut the side of my rods and it just killed any chance for correct oil pressure...
