No oil pressure at idle after rebuild, new block!

[bison]

did you verefy oil press with a manual gauge????

Did you check if the piston oil cooler jets are in place?(only on 605 blocks)

how much brg clearance? rods, mains and cam..

did you Check oilpump drive and block bore fit?

check oilpump and maincap mating surface for being flat.

I would also inspect the oil pump and relief valve.

 

[turbovanman]

did you verefy oil press with a manual gauge????

Did you check if the piston oil cooler jets are in place?(only on 605 blocks)

how much brg clearance? rods, mains and cam..

did you Check oilpump drive and block bore fit?

check oilpump and maincap mating surface for being flat.

I would also inspect the oil pump and relief valve.

Yes, manual gauge, big fat 0 hot engine.

Its a 97 block, had great oil pressure but worn out. I am not sure if he verified they hadn't fell out.

I am not sure on the clearance-have to ask but well with specs, he said even he tigthened up the rods.

Yes, checked as thats how we found how loose the new block was.

Yep, flat as a board and I use anerobic sealer for extra measure.

I pinched off the cooler lines and oil pressure didn't change, so the pan is coming off and inspect the new pump. I might install the OE pump as I am getting frustrated and running out of time, :sad:

 

[turbovanman]

Well I disconnected the turbo oil feed, no difference.

Bypassed the oil cooler, NO difference and hows this for shit's and giggles, I pinch off the feed line to the oil cooler and the oil pressure, whats left, drops to 0???????????????

We took apart a GM hi volume spec pump-oil squirter unit and its nothing more than a stock 96 with a 1/2 plate added????????? How the hell does this become a hi volume pump using the same size oil gears????

 

[gmctd]

IIRC, oil feed is pump to cooler from cooler to block galleries, incl oil pressure gallery - if you have a 6.2 vacuum pump laying around, cut the top section off such that you can get on the shaft with a VSR 1/2" drill - use that to check oil pressure without running engine, will easily drive to full pressure - hi-volume oil pump should have longer gears by ~1/4"

Also, I've not found any tapped holes in these blocks to be english thread sizes - they're all metric, starting with the 6.2 - some english sizes fit, such as 9/16" in the bellhousing holes, but the correct metric bolt is tighter, more secure, as it should be

I did find 9/16" bolts in the neighbor's '83 6.2L Sub, after some idiot in arizona stole his Diesel 700R4 and t\c, replacing it with a gasser (pattoie!) 700R4 and t\c, rather than just adjusting the TV cable - talk about yer slushbox, that hi-stall t\c ain't handling Diesel torque very well.............

 

[turbovanman]

IIRC, oil feed is pump to cooler from cooler to block galleries, incl oil pressure gallery - if you have a 6.2 vacuum pump laying around, cut the top section off such that you can get on the shaft with a VSR 1/2" drill - use that to check oil pressure without running engine, will easily drive to full pressure - hi-volume oil pump should have longer gears by ~1/4"

Also, I've not found any tapped holes in these blocks to be english thread sizes - they're all metric, starting with the 6.2 - some english sizes fit, such as 9/16" in the bellhousing holes, but the correct metric bolt is tighter, more secure, as it should be

I did find 9/16" bolts in the neighbor's '83 6.2L Sub, after some idiot in arizona stole his Diesel 700R4 and t\c, replacing it with a gasser (pattoie!) 700R4 and t\c, rather than just adjusting the TV cable - talk about yer slushbox, that hi-stall t\c ain't handling Diesel torque very well.............

I hate to argue but the motor mount bolts and bellhousing bolts are 3/8 course and always have been, :thumbsup:

As for the oil pump, we found the 96 spec and you are correct, they are aprox 1/4 longer but still find it hard to understand that that is enough to make up for the oil squirters. Also still can't figure out what the 1/2 plate is for???????????????

Just pulled the pan off, inspected the Melling pump, looks ok but the plate surface is pittted-looks like a 2 year old put it together. Putting in a known good used GM pump as we have nothing left to try. We also stretched the relief valve spring a tad.

 

[turbovanman]

I have better hot oil pressure but still no idle oil pressure. This is )*&)&*)*& messed up, :sad:

 

[bison]

FYI the later(96 and up) blocks are mainly metric,thats a fact. 10mm for the bellhousing.

I suspect some or all the oil cooler jets are missing.

brg clearance should be 2 thou.

you need the high volume pump to get any decent oil press,take the thing apart and check gear clearance and lap the gear flats and pump body and plate to get as close a fit as possible.
you can also flip the gears if the other side of the teeth are better

 

[turbovanman]

FYI the later(96 and up) blocks are mainly metric,thats a fact. 10mm for the bellhousing.

I suspect some or all the oil cooler jets are missing.

brg clearance should be 2 thou.

you need the high volume pump to get any decent oil press,take the thing apart and check gear clearance and lap the gear flats and pump body and plate to get as close a fit as possible.
you can also flip the gears if the other side of the teeth are better

Yes, they are metric EXCEPT motor mount and bellhousing bolts. I have been a GM tech for many a year and this has the original bellhousing bolts. The engine side are standard, the stud on the other side is metric. These blocks are based off the big block 502. I've checked the bolts with a tap and die and metric won't fit, 3/8 course works no problem and this is ON the factory 97 block.

He said he checked all the jets and blew thru them, so I guess we'll find out tomorrow. I am just pulling it out now. If they are all there, we are plugging them off.

We are running the HV pump and I've tried 2, with almost the same results, a good OE and a Melling. We did the gear up and down test, not very nerdy but they both felt exactly the same.

I've done pre jet engines before with NO issues so I believe for some reason, this is our issue, I've eliminated all other issues.

We are going to do an oil pressure test tomorrow first, hang a bucket off the oil pump pickup and spin the oil pump with the pan off and see if anything is obvious.

 

[bison]

well man,i done a number of them and havent seen a 97 and up with standard tread yet.

i have also never experienced the prob you seem to have. if clearances are tight,jets are in,oilpumpdrive is close fit,oilpump and relief valve is good and leakfree at the mainbrg mount pad,pickup tube is tight in the pump bore, all oil gallery plugs are in.all cam brgs are installed with proper clearance and oil feed holes lined up with the block holes,All o rings are on the oil filter adaptor bolt + a good filter,and turbo seals are good. Then you have to have good oil pressure "period"

 

[turbovanman]

well man,i done a number of them and havent seen a 97 and up with standard tread yet.

i have also never experienced the prob you seem to have. if clearances are tight,jets are in,oilpumpdrive is close fit,oilpump and relief valve is good and leakfree at the mainbrg mount pad,pickup tube is tight in the pump bore, all oil gallery plugs are in.all cam brgs are installed with proper clearance and oil feed holes lined up with the block holes,All o rings are on the oil filter adaptor bolt + a good filter,and turbo seals are good. Then you have to have good oil pressure "period"

I am too tired to argue over the bellhousing bolts at this point and this isn't the thread for it.

Don't you think we know, he builds engines for a living, he's gone over this last engine a 100 times before he gave it to me, something weird is going on, for this too happen on 2 blocks? Maybe the crank is bad? I just don't know anymore.

So your saying because its never happened to you, it can't possibly happen to anyone else? That's messed up logic at the best of times.

If we find the issue, I'll post up the fix, if not, we'll get a reman from someone and chalk it up to a ****ing disaster.

 

[nobby]

OK so here is something interesting, you said that when you pinched off the oil cooler feed line the pressure dropped off to zero. That should not happen the cooler has a bypass valve to protect it from high cold start up oil pressures, it also means that as some have done if you remove the cooler and plug the feed and return ports on the block you will still have oil pressure to your engine via the bypass valve. My thought are this:

1. Assuming a good cooler bypass valve your problem is early on in the system not clearances/missing plugs. If you had good pressure from the pump with a leak down the line somewhere then pinching off the feed line should not have any effect or only a slight one on system pressure.

2. If you have a faulty cooler bypass valve then you would experience the pressure drop off when pinching the feedline and the issue could be bad pump or a poor clearance/leak somewhere. What are the odds of a faulty cooler bypass valve and an issue somewhere else?

You are certain that the pump is not sucking air on the suction side of the pump? You already mentioned anerobic sealer on the discharge side. The regulator rather than stretching the spring get a new one and how does the valve and seat look?

Cheers
Nobby

 

[bison]

I read your post on DP, and seen that these blocks are chinese,by itself no problem.
but I found that some of the factory installed cam brg are way outa specs in some of these blocks( depending on the manufactorer,there is 3 diff ones that i know of).
Mebby you should check into that.Best to pull them out and install a new set.

How tight is fit of the oilpumpdrive in the block? as to loose a fit can pass a lot of oil there outa the lifter oil gallery.

I apriciate your frustration,I just try to help pinpoint your problem.Obviously some one is missing something.No need to get frosty.

 

[turbovanman]

OK so here is something interesting, you said that when you pinched off the oil cooler feed line the pressure dropped off to zero. That should not happen the cooler has a bypass valve to protect it from high cold start up oil pressures, it also means that as some have done if you remove the cooler and plug the feed and return ports on the block you will still have oil pressure to your engine via the bypass valve. My thought are this:

1. Assuming a good cooler bypass valve your problem is early on in the system not clearances/missing plugs. If you had good pressure from the pump with a leak down the line somewhere then pinching off the feed line should not have any effect or only a slight one on system pressure.

2. If you have a faulty cooler bypass valve then you would experience the pressure drop off when pinching the feedline and the issue could be bad pump or a poor clearance/leak somewhere. What are the odds of a faulty cooler bypass valve and an issue somewhere else?

You are certain that the pump is not sucking air on the suction side of the pump? You already mentioned anerobic sealer on the discharge side. The regulator rather than stretching the spring get a new one and how does the valve and seat look?

Cheers
Nobby

Yeah, that one stumps us, as the feed passage is shared to the cooler and to the top end.

The relief valve was free and no marks.

I read your post on DP, and seen that these blocks are chinese,by itself no problem.
but I found that some of the factory installed cam brg are way outa specs in some of these blocks( depending on the manufactorer,there is 3 diff ones that i know of).
Mebby you should check into that.Best to pull them out and install a new set.

How tight is fit of the oilpumpdrive in the block? as to loose a fit can pass a lot of oil there outa the lifter oil gallery.

I apriciate your frustration,I just try to help pinpoint your problem.Obviously some one is missing something.No need to get frosty.

He mic'd them before installing the cam.

At this point, its out again, we are rigging up a system to pressurize it and run some thin oil thru, IE 5w20 or a mix of oil and WD40 and look for some leaks, I mean we are literally loosing 20 psi of oil pressure at idle????????

Not getting frosty, just tired and fed up, and just don't want to argue over stupid stuff, :thumbsup:

Thanks for all the suggestions, at this point, its just a mystery, I mean 2 blocks, one chinese, one OE and they are doing the exact same thing, :mad2::mad2:

 

[bison]

Yeah, that one stumps us, as the feed passage is shared to the cooler and to the top end.

The relief valve was free and no marks.



He mic'd them before installing the cam.

At this point, its out again, we are rigging up a system to pressurize it and run some thin oil thru, IE 5w20 or a mix of oil and WD40 and look for some leaks, I mean we are literally loosing 20 psi of oil pressure at idle????????

Not getting frosty, just tired and fed up, and just don't want to argue over stupid stuff, :thumbsup:

Thanks for all the suggestions, at this point, its just a mystery, I mean 2 blocks, one chinese, one OE and they are doing the exact same thing, :mad2::mad2:

one more suggestion,could there be a collapsed hose to or from the cooler,i mean inside the hose loose rubber that partially closes the bore when the oil heats up?

 

[nobby]

one more suggestion,could there be a collapsed hose to or from the cooler,i mean inside the hose loose rubber that partially closes the bore when the oil heats up?

Collapsed hoses to or from the cooler should not have this effect, as I said in my earlier post any blockage in the cooler circuit would be dealt with by the cooler bypass valve which will ensure oil feed to the engine still.

So what exactly are you sharing between the two engines, using the same oil pump perhaps? The odds of both blocks independantly sharing the same issues hmm. Could it be that you have a bad new HO pump and that the GM one you tried was itself worn out but behaved a little better.

Cheers
Nobby

 

[turbovanman]

FIXED!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Well we rigged up an external oil pump, blocked off the OE oil pump pad, hooked up to an oil galley and pressurized the block, we emptied 7 quarts of oil in 15 secs, The oil squirters are like waterfalls, its just pouring out so that's the problem. We are just going to plug them off. I just can't explain how or why 2 blocks did this?????????

I guess another all nighter after I get the engine back in a few hours, :sad:

 

[bison]

Collapsed hoses to or from the cooler should not have this effect, as I said in my earlier post any blockage in the cooler circuit would be dealt with by the cooler bypass valve which will ensure oil feed to the engine still.

So what exactly are you sharing between the two engines, using the same oil pump perhaps? The odds of both blocks independantly sharing the same issues hmm. Could it be that you have a bad new HO pump and that the GM one you tried was itself worn out but behaved a little better.

Cheers
Nobby

so,why can that have no effect?
Oil path is from pump to cooler to filter to oilgallery and brgs,if filter plugs oil goes trough bypass.
If the hose to or from the cooler gets restricted by a piece of rubber,( more so mebby when the rubber becomes more plyable when the oil gets hot)pressure gets passed trough the pump relief valve. but not enough oil reaches the brgs and press stays low.

 

[nobby]

so,why can that have no effect?
Oil path is from pump to cooler to filter to oilgallery and brgs,if filter plugs oil goes trough bypass.
If the hose to or from the cooler gets restricted by a piece of rubber,( more so mebby when the rubber becomes more plyable when the oil gets hot)pressure gets passed trough the pump relief valve. but not enough oil reaches the brgs and press stays low.

As I mentioned in my prior post the oil cooler has its own bypass valve separate to the filter bypass valve. This is done primarily to protect the cooler circuit from high oil pressures when the oil is cold on start up during winter etc. This will also then serve to allow oil flow should the cooler circuit become blocked. I have read of those that have in the past removed the cooler and lines and plugged the line ports (in anguish over the pesky stock line leaks) with no loss in lubrication etc.

Cheers
Nobby

 

[turbovanman]

As I mentioned in my prior post the oil cooler has its own bypass valve separate to the filter bypass valve. This is done primarily to protect the cooler circuit from high oil pressures when the oil is cold on start up during winter etc. This will also then serve to allow oil flow should the cooler circuit become blocked. I have read of those that have in the past removed the cooler and lines and plugged the line ports (in anguish over the pesky stock line leaks) with no loss in lubrication etc.

Cheers
Nobby

Yes, the oil cooler does have a bypass but we figure the oil pressure was so low, it couldn't make the bypass so to speak.

 

[nobby]

Just glanced through my manual for info on the nozzles, did not find much except the observation that certain cleaners can damage the nozzles.

Cheers
Nobby