Main bearing replacement??

[mycarsucks]

Car is really low on oil pressure after warming up. tried all the tricks, now I assume its the main bearings.

I have never replaced these before. I know how to install them on a freshly machined block. I guess Ill number the questions.

1. Will I have to get the block line bored?
2. Is there anything that I can't do in my garage?
3. If I have the engine out is it minor enough to just do this or should I consider a complete rebuild?
4. Would this be a good time for a cam swap?
5. Why did this happen to me? I finally got this hot-air intercooled....

PS This thing was supposably rebult about 20k ago, hopefully he just did it the loose chevy way, so consider that it might be semi rebuilt when answering # 3

 

[Intercooler]

1. Maybe or Maybe not but I really doubt it.
2. No
3. May have to dig a little to figure this one out. Putting new main bearings in is a decent amount of work. If I had it out I think a freshen would be in order.
4. What do you have now? If you feel you need it but most like the stocker.
5. May never fully understand this question/answer.

Nope on the Chevy thing! I have built them .003" down to .0015" and have had decent (above 14 PSI hot idle) oil pressure. What are you getting?

 

[mycarsucks]

What would a freshen entail by your definition. I am considering the full rebuild kit from summit for around 450. What should I expect from the machinist for price??

The 5th question is just me blowing off some steam. I finally threw an IC on it and was planning on having some fun.

Well, I threw some 20w-50 in and a booster plate to see if I could remedy the situation. I probably see 50-60 cold idle. after a good long drive im 4-5psi in park and 0!!!! psi in drive........ Needless to say Im not driving it.

 

[Intercooler]

Are you using a mechanical gauge? Did you double check it with another gauge? Did this happen all of the sudden?

 

[mycarsucks]

No, I have a digital dash, and the oil pressure light has always flickered after running the car for a while. So did the volt light though, so I would tap the dash and the volt light would turn off. I bought this mechanical gauge to see if the idiot light was correct. When I see 0 psi on the gauge, I do see the oil start to drop in the tube....

 

[Red Regal T]

If oil pressure is the only problem you're having, why not try a hi-volume oil pump before you pull the engine. Use the heavy relief spring and port your oil passages.

If it's not using oil, why not pull it and just replace the mains and rod bearings. Bearings are cheap. Plastigage it to make sure your clearances are .0015 to .002.

Everything depends on how much you want to spend and how much time you want the car to be apart. What I've suggested can be done for under $300 easy.

 

[mycarsucks]

for under 300? Is this having someone else do it? I thought bearings were far cheaper than that. Am I missing a hidden cost?

 

[Red Regal T]

What are you complaining about? That's just a safe number to include anything you might do and a lot cheaper than $450 from the chevy suppliers. You also have some gaskets, rear seal, possible timing chain, etc........I don't know what you may decide to do.

 

[mycarsucks]

Oh, I'm not complaining. I thought I had my IC project all cost mapped out and found a few hidden costs that weren't expected. As I have never done this I expect a few.

So, if I do replace the bearings is there a way to measure it up so I know I'll get the right bearings the first time?

 

[Red Regal T]

Unless you have a machinist friend, all you can do is buy a pack of plastigauge and check your bearing clearances with that. You're looking for clearances of .0015 to .002 for good oil pressure. If much bigger you'll have to have the crank cut and go with the next size bearings.

 

[Turbo Brian]

You also could be losing oil pressure at the front cover. If the aluminum cover is worn and has excessive clearance to the oil pump gears, your pressure can also be low when hot. A new/tight cover might solve your problem.