Oil Pressure and Connecting Rod Clearances

BajaT4 · Post by **BajaT4** » Sun Mar 05, 2006 7:20 pm

As my engine warms up, I gradually lose oil pressure. At 180 degrees I need to keep the engine above 1000 RPM or the light goes on and the gauge reads about 5 psi. This hasn't always been the case.

Engine is a 2270, DPR crank, CB type 1 H beam rods, Web cam, Raby balanced, etc.

Summer of 2004 my engine developed a knock which ended up being a piston pin too tight which caused the connecting rod to wear .008" into the crankshaft. The rod was also worn about the same .008". I replaced the rod, had Jake rebalance all of the rods and replaced the rod bearings. Rod to crankshaft on 3 of the 4 rods is about .020" and the fourth is .028"

Early 2005, I had a sticking pressure relief plunger problem that resulted in ZERO oil pressure. I cleaned up the plunger seating area with an end mill and shimmed the heck out of the plunger. I did limp home about 5 miles with the OP light

on but do run synthetic oil.

I've got the engine apart now with the intent of putting a full flow setup on it BUT I also need to fix the oil pressure issue. .028" is at the high end for rod endfloat limits. Should I get the crank repaired and will that fix the oil pressure problem or should I be looking somewhere else?

OriginalCustoms · Post by **OriginalCustoms** » Sun Mar 05, 2006 9:44 pm

Another thought is to check the oil pump to case clearances. I've heard of a couple of cases that were too large for the oil pump and resulted in low oil pressure. Just another thought.

BajaT4 · Post by **BajaT4** » Mon Mar 06, 2006 5:01 am

Good point. Before I took the engine apart, I pulled the pump and checked cover to pump and case to pump clearances. All good.

MASSIVE TYPE IV · Post by **MASSIVE TYPE IV** » Mon Mar 06, 2006 5:53 am

.028 is a bit too open for me... Typicaly my engines run with .018-.020.

I would check the internal oil pump clearances as well.

At this point it's hard to say what the best remedy would be- let me think about it.

BajaT4 · Post by **BajaT4** » Mon Mar 06, 2006 4:09 pm

Actually, I'll be purchasing a new pump from you in the next month so the oil pump won't be a problem!

BajaT4 · Post by **BajaT4** » Wed Mar 08, 2006 6:51 am

My plan was to get the crank welded locally by a crankshaft shop. As long as they replace material in the groove, balance shouldn't be an issue. With a Raby pump kit, new bearings since the engine is apart anyways and the .008" gap filled, I would think that my oil pressure problem would go away. Those are the only variables that I can see that changed.

I think the crank was modified by DPR originally. I would feel a little more confident in sending the crank to them for repair or do you have anyone else that may be better qualified at this type of repair?

seahag · Post by **seahag** » Wed Mar 08, 2006 9:49 am

I would suggest returning it to the original maker and let them remedy the problem. After all it is their product.

dstar5000 · Post by **dstar5000** » Wed Mar 08, 2006 11:13 am

I'm sure DPR would rather you send it to them.

Don

BajaT4 · Post by **BajaT4** » Wed Mar 08, 2006 6:33 pm

Jake do you have contact information for DPR?