I have been having problems with losing oil pressure in my stock 355 motor when it gets warmed up. Here is the short version of what is happened and happening.

I bought the car last fall and everything was fine. When we started it up this spring it had a knock. We took the motor all apart to find a badly spun bearing. We took it to the machine shop and had it rebuilt and the crack turned to 30 over and all that.

Now it sounds awesome but whenever it gets warmed up it looses oil pressure bad. We have changed oil pumps. (still just have a stock pumped in it but a new one.) We started with 10w - 40 oil then went to straight 30 and now straight 50 and still has the same problems.

When it is cold it gets about 40 lbs at idle and goes up under power. But as it warms up it loses pressure down to about 15 and below on the track. Then when we pull it in it is under 5 at idle. Let it sit for a while and it is back to 40.

So we took the motor back out today and looked at all the new crank bearings. They look normal to us. The have a few grooves but then dont look bad. Going to take them to the machine shop tomorrow to have an engine guy look at them.

But really we are kinda stumped on what can be causing this. Just hoping someone on here might have an idea to help us out. This is our first year racing and we have pretty much been plagued by this same thing all year.

Thanks for any suggestions

It goes up after cooling off because as the oil gets cooler it doesn't flow as well which raises the pressure.

It sounds like you have a pressure leak somewhere in the motor. The most likely cause is too much bearing clearance. But I would check everywhere to make sure oil isn't leaking internally somewhere else.

With the crank and rods installed, the cam still in and the heads, lifters, and rockers all on the engine, pressurize the oiling system and look for a big leak. You can do this by removing the fitting where the oil pressure guage goes and using a rubber tipped air gun, blow compressed air into the hole. With the intake manifold, valve covers, and oil pan removed, you can look for any place where there is a lot of air escaping. If it seems to be mostly around the main bearings or perhaps just one in particular, there's your problem.

-Maurice

WHat do you use for filters? Also, are you using oil restrictors? I'd take them out especially in a 355, not turning the motor hard.

This may sound dumb, I had the same problem at the end of last season. We changed the oil filter and the pressure came back up to normal. WE jsut had a plugged..although brand new, oil filter. Maurice does have a point. I'm no professional by no means, but lack of pressure could be clearences are wrong.

Make sure the 1/2" plug is under the rear main cap. Most shops take these out for cleaning the block.

Were new cam bearings installed and do you run an oil cooler? If you have a cooler on it, remove it and try w/o.

If you have a Fram filter on it throw it away and put one on made by Wix, CARQUEST or NAPA.

I Have seen more than one person have this problem with those Orange filters, but they sure like the grippy thing on them LOL.

Gov

We have used a Fram racing filter for along time and have no problems with them.

The motor we started out this year with, we eventually took it out to run bigger one and when we needed to use it again, during the first race we had it in, the oil pressure gauge was jumping all over, I put a new filter on before he went out for the feature and it never had a problem until it grenaded about 3 weeks ago, that had a wix on it. Broke 4 pistons, snapped the crank and cam in half, broke the block, oil pan and all 8 rods are junk.

Not being a chevy guy, isn't there something about o-rings on the distrib shaft could cause low press?

MPR72

Yep those orange filters is what we had problems with too. We were told to use Wix filters and havents had an issue. Carquest filters are made by wix as well.

I can't comment on the pressure loss but I know I've been looking very closely at oil filters.

Most of the ones I've been looking at are for Neon's but the construction of the filters is all the same. EVERY source I have found has said to avoid the Fram filters and they all cite the cardboard caps for the filter material as why.

Here is a link to a gentleman named Russ Kinze's site. He cut apart ALOT of filters and compares them. He did it in 1999 and he did it again in 08 and shows the difference. The link is to his opinions on filters but if you look around the rest of his results can be found. There is detailed pictures and explanations for each filter.


http://www.knizefamily.net/minimopar/oilfi...s/opinions.html


I know his work and a few others I've found have convinced me to never buy another Fram filter!!!

Read this, I bet you never put an orange filter on anything you own again. I have freind that had the same problem. I use Purolator based on this study and the good price. The link is to an independant oil filter study conducted by a racing team not so different than any of us. hey dig it my Bulldog bro came up with the same link!!!!

http://www.knizefamily.net/minimopar/oilfilters/index.html

(We have used a Fram racing filter for along time and have no problems with them.)


The Fram RACING filter may be OK, as the ones I have seen go bad were the off the shelf, Wal Mart / Farm & Fleet units.

I use the regular CARQUEST / Wix filter not the racing filter and have also cut appart some competitive units.

After seeing the inside of some of these I will always stick with a premium filter. How can anyone even think of putting a 2.50 filter on ANY race engine.

Gov

Had 2 new motors this year that were dropping pressure rapidly during break-in, They both had Fram filters, That was the problem on both. No more frams around here for sure.

I use about a $5.00 filter. The Pure One, Advance is closer down the street than NAPA. and it has comparable guts to the wix, the minivan gets a regular Purolator.

Blaming the oil filter brand will rarely solve an automotive techinical problem. I would assume this low pressure problem caused the spun bearing from last year. 40 psi at idle cold is NOT sufficient,a stock motor has more cold. Like Dan said check the plug under the main cap,they are aluminum and dissolve in the hot tank and may not even be there but check the plugs under the cam timing gear they may be missing also. The oil pick up could be too close to the pan. Spot weld a 1/4 nut to the bottom of the pickup screen to make sure you have enough clearance. Check for a stuck pressure releif spring in the oil pump bottom cover. A cam bearing not completely installed or pushed in too far will cause oil to be bled off quickly. Look and make sure they are all about the same depth on both sides,one wrong will stick out on closer examination. Lifters that sit too low will bleed off oil pressure,this can be seen by looking at the bottom of them. If you see the recessed groove from below this is a problem.

Yes there is. I had the same issue a few years ago. Dug out my distributor box and found the O-rings. Put them on the shaft and I was back in business.

One more thing. DAN how can you suggest NAPA junk parts to anyone???? SHame on you. I use regular C-Q oil filters. I don't even work there.

I pulled out a fresh racing motor and tore it apart because of low oil pressure. It turns out it was just that dang Fram Oil filter!

Because Carquest and NAPA filters are both manufactured by DANA/WIX.

before i tore anything apart, i would take the oil line off that feeds the gauge and make sure it's not restricted. then i would try another gauge.

steve "pops" pastorino

Ditto, lots of guys do not know about the " mystery plug",,,lots of guys never remove and replace it after blowing an engine and blow the engine again because lots of bad stuf gets trapped under this plug, then goes thru the engine after it is repaired.

PS,,,I did not know about the bad rep FRAM has now, i will change to Wix,,Thanks all

also you Lead sled guys need to use a Stock looking oil pan that is modified for Oval racing to make your engines live...

see...

http://www.competitionproducts.com/products.asp?dept=1259

Thanks for all the help everyone.

First we are on our 3rd filter we have heard the bad things about fram which was the first one we had in. then we had a carquest and now we have bosch.

We had the gauge checked at the track last time we hooked up a guys portable gauge and it read the same thing the in car gauge said.

We think it could be the clearances we talked to a motor guy about them and he said that one groove on one bearing like we have wont hurt but with all of them like that it is more then likely our issue.

Still going to check all the things you guys said to try first but if i cant find anything going to get a stock crank and bearings and put in and see what happens.

Dick,

I try not to use this discussion board to advertise and as Rocky says they both come from the same place.

That is why you will see me make reference to more than one brand on occassions.

Sure there are times when I will reference my employer, as I am also a stock holder.

I'm sure your remark was more in humor, LOL!!!!!!!!!!!!!

Are you going to the Zoo tomorrow to tune up for Wed & next Saturday??

Trick,

I have seen at least 4 Fram filters collapse to the point of the media trying to be sucked up into the filter mount / inlet.

Mind you this was not on the HP series that Fram sells.


Dan

another thing to look for if your motor guy hasn't already done is in the oil filter adapter by pass. Take it out and plug it with a screw in plug... also as everyone else has stated , use a good wix- carquest filter...

I used the A1 system in both my super and superpro car and never had a oil press drop problem and all you do is cleanit and reinstall. About $200 but you never have to replace it and it has micro sreens . Easy to check for debris after every nite.

I thinkin to mush bearing clearance . Ok when the oil is cool and a little thicker but heats up and thins out. Run royal purple or the like and see what happens . Dont run mobil 1.

Does the motor run well?

A little misfire or a real rich mixture could be thinning out the oil while you're racing. Just a thought.

Mike

The motor runs and sounds great. Like i told the motor guy if it wasnt for the gauge i would have no idea anything was even wrong.

We checked all the plugs and everything.

We looked in the distributor and didnt really see an o-ring. We hoping someone could give me a little more info on that if possible.

There is a lot of things that can cause oil pressure problems... Let's start at the bottom. main clearance, rod clearance, rod side clearance,surface between oil pump n rear main cap, oil plugs in rear of block, but not likely.Oil plugs in front of block, cracked main cap or crack in main web. With a .030 crank my guess would be too much rod side clearance let me know what you find Pressureizing the oil system with the pan off is good idea.