Stumbling, low oil pressure, predetonation
June 14th, 2012, 11:54 PM
#11
While the belt was off, I pushed and pulled on the crank pulley, and it moved slightly up and down, not like a bad roller bearing, but it did give a little. Not exactly a scientific check, but I wonder if that indicates bad main bearings and that looseness is what is throwing the crank sensor code? But if the bearings where that bad, surely I'd hear low end noise?
It's more likely that the pulley had some play in it, but drivebelts can act as a sort of vibration dampener for a sloppy crank (and keep them from "walking" around the bearings.
June 15th, 2012, 6:42 AM
#12
Thanks.
UPDATE: I took the engine cover off and noticed a vacuum hose was collapsed. Also the PCV valve was noisy and the elbow into the upper manifold vacuum doodad was cracked. I fixed all that and took the van for a ride.
NOt a single stumble or miss or predetonation, even under heavy load up a hill at 60 mph!
HOwever, the CEL did come on and flash for about 20 seconds after that ride up the hill. But then it stopped flashing again.
The oil pressure is still low (obviously) so I'm going to put on a new high volume oil pump and see how it goes... thanks for the help.
UPDATE: I took the engine cover off and noticed a vacuum hose was collapsed. Also the PCV valve was noisy and the elbow into the upper manifold vacuum doodad was cracked. I fixed all that and took the van for a ride.
NOt a single stumble or miss or predetonation, even under heavy load up a hill at 60 mph!
HOwever, the CEL did come on and flash for about 20 seconds after that ride up the hill. But then it stopped flashing again.
The oil pressure is still low (obviously) so I'm going to put on a new high volume oil pump and see how it goes... thanks for the help.
June 19th, 2012, 8:16 PM
#13
OK, update time.
I replaced the oil pump, and I now have excellent pressure! above 20psi at idle, and goes up to 60 when driving. Pretty cool, especially considering a highly qualified and experienced mechanic told me it needed a new engine. Seriously people!
The problem with the old oil pump seems to have been the pressure relief valve spring had failed, so it was simply letting the oil recycle in the pump. So much hassle for a spring!
I replaced the oil pump, and I now have excellent pressure! above 20psi at idle, and goes up to 60 when driving. Pretty cool, especially considering a highly qualified and experienced mechanic told me it needed a new engine. Seriously people!
The problem with the old oil pump seems to have been the pressure relief valve spring had failed, so it was simply letting the oil recycle in the pump. So much hassle for a spring!
June 21st, 2012, 8:12 PM
#15
If I had to do it again, would probably take me 2.5 hours from start to finish. It's not hard.
Jack the van up
Remove the cross member below the oil pan
Remove the starter
loosen the bolts on the pan - get the two bolts hidden at the back of the oil pan by two rubber grommets.
Remove the wires on the passenger side, and the oil level sensor electrical connection
Remove the pan
One bolt holds on the the oil pump. Get the old oil screen off while the oil pump is on the engine - more leverage.
Having said that, my oil pressure is not as good as I originally thought, but it is about twice as good as it was, so I'm happy. I put 2 pints 5-30, 1 pint lucas goop, 1.5 pints 10w40, so I can't be absolutely sure it was the oil pump, but I'm pretty sure.
I used the high volume melling H155HV pump, and the iss-55 (or something like that) steel shaft replacement.
Good luck, it's not hard.
Jack the van up
Remove the cross member below the oil pan
Remove the starter
loosen the bolts on the pan - get the two bolts hidden at the back of the oil pan by two rubber grommets.
Remove the wires on the passenger side, and the oil level sensor electrical connection
Remove the pan
One bolt holds on the the oil pump. Get the old oil screen off while the oil pump is on the engine - more leverage.
Having said that, my oil pressure is not as good as I originally thought, but it is about twice as good as it was, so I'm happy. I put 2 pints 5-30, 1 pint lucas goop, 1.5 pints 10w40, so I can't be absolutely sure it was the oil pump, but I'm pretty sure.
I used the high volume melling H155HV pump, and the iss-55 (or something like that) steel shaft replacement.
Good luck, it's not hard.
Thread
Thread Starter
Forum
Replies
Last Post
Eric Sherden
Caprice
2
September 24th, 2013 1:21 PM
not_a_car_dude
Tahoe & Suburban
4
September 15th, 2013 7:41 PM
midnight rumbler
General Tech
0
October 10th, 2009 9:14 PM
