main bearings

[camio54]

I have a 400 sbc with low oil pressure. I have replaced the oil pump, filter ect. I am told it is most likely the main bearings. Does this usually invlve any machine work on the engine? The motor runs great otherwise. lucas oil is keeping the pressure up for now. Maybe not the best solution, but a temporary one at least.

 

[wrecker55]

main and cam bearings will cause pressure loss, pull rear main cap and see if bearing has moved as it will block oil passage if it has, should be locked in with tabs, i just had that problem last week and it was a fram filter that caused it

 

[Tripper]

Pressure

54,
What's u're pressure @ idle & @ speed, r u sure u're gauges are operating properly & is this a new issue? Also, what kind of motor r u talkin' about?!

BoB

 

[Sam_Fear]

I'm with Tripper - don't trust an electronic gauge use a mechanical to check it. Could be the gauge/sensor are not that accurate.

 

[camio54]

gauges

I do have an electric gauge(stewart warner). I checked that with a air pressure line with a regulator and gauge and it read correct. I also checked the pressure with a hydraulic one and got the same reading.

With out running the Lucas Tar, the pressure drops to zero at idle. I have to keep the engine running at least 1200 rpm at a stop light which of course make the engine run too hot. With the truck going down the road it is in the 30-40 pound range. It would be nice to have a hot rod that can handle city traffic.

This is a 70's era 400 cu SBC. I took it out of a land yatch impala.

Thanks for all the coments. Your help is appriciated.

Here is an ignorant question. Can the main bearings be changed with out pulling the engine?

 

[adam]

If you're running a fram Filter, the first thing to do is junk it and put on a wix (or anything else, really) filter-that might fix the problem. If that's not it, anything else will be a band-aid that you will never know if you can trust. Pull the motor and go through it.

 

[moronthethrottle]

Oil pump?

Can the main bearings be changed with out pulling the engine?

It may be possible depending on location of your crossmember, but is certainly not recommeded. It's actually easier to just pull the engine and change the bearings on an engine stand.

 

[moronthethrottle]

Oh yeah, welcome to RRR. I travel to Omaha several times a year, I'll have to look you up and check out your build(s)!!