longest run since rebuild.......couple of problems !

[VettePaul]

Hi Guys. Went to a show today 140 miles from home. I used a pint of oil on the journey there. On the way back I up'd the revs as I've done around 500 miles since rebuild. I stopped half way home to check the oil and when I lifted the hood oil has been coming out of the aftermarket breather in the valve cover and spraying it everywhere :confused. The aftermarket breather is like a little filter in a chrome case that just pushes into the top of the valve cover. It was bone dry on the journey down there but seems to have got worse from reving higher. One good thing though..........got trophy for best on Corvette Club stand :J Any idea's anyone. VettePaul.

 

[wolf_walker]

Valve cover baffeled inside?

A real PCV system is always a good idea, even if it isnt very pretty.

 

[69MyWay]

I am with Wolf, I think you may have a problem in the PCV system. If you don't have one, or it is not working right, the pressure in the engine would build up and possibly blow out that breather. The PCV keeps a good flow of pressure through the crankcase to keep the internal pressures in check.

 

[VettePaul]

Thanks for the reply Guys. The valve cover doesn't have a baffle inside but it is the same breather and valve cover etc from before the rebuild. Could it be that I now have a high pressure/volume oil pump ? I have a pcv valve in the opposite valve cover which hooks up to the carb then on this side it just has the fancy looking breather. As I mentioned earlier, all as b4 rebuild..VettePaul.

 

[69MyWay]

Well, if you are blowing that much oil back out the cover, something is wrong.

What kind of oil pressure are you pushing? Any leaks from the front or rear main seals?

 

[VettePaul]

It's pushing 80Ib pressure most of the time. There are no leaks from anywhere.:confused .Paul.

 

[mgms_1968]

I would think that 80 psi is to high.

If you paid someone to do the rebuild I would be calling them ASAP!!!!

If you did it your self then I would start then a few questions?

q1 what kind of oil pump and pan capacity?
q2 What is the engine?
q3 Are you seeing smoke out of the exaust?

You also might want to do a compression test on each cylinder?

 

[VettePaul]

I was told that the high oil pressure gauge would peg at 80Ib. Everything has been fine until I stepped up the revs a bit more. Could this be just a small problem like there being no baffle in the valve cover under the breather........Here's hoping ! VettePaul.

 

[JHL]

Hi Paul,

Sorry I didn`t catch up with you at the weekend as usual I was totally disorganised and didn`t make it down. Maybe I will catch up with you at another day out and hopefully will have the car sorted out.

With regards to your problem I have open Edelbrock breathers on my rocker covers and there are no baffles either. I don`t get any oil blowing out on that scale. It sounds like you are using it and loosing it. Having a PCV set up would only suck the oil that is being blown out back into the inlet manifold and not address the problem. If you did have a closed PCV system and for some reason it got blocked up then you would have problems with seals and gaskets or in some case it blows the push in oil filler cap off or blows oil out the dipstick.

I will go with mgms and suggest a compression test, did you have the engine bored and replace the rings & pistons ???. This is usually the symtom for an engine with high miles on it and worn bores or rings. For a quick check pull out the breather and give the engine a few revs and if you can smell stong exhaust fumes coming out of the valve cover, the gases are probably getting past a ring and pressurising the crankcase or possibly a bad valve. I`m not so sure that high oil pressure alone would cause your problem but some of the more knowledgable guys might be able to tell you for sure.


J.

 

[Tom Bryant]

I agree with John. It sounds like a blowby problem from poor ring sealing. A compression test and, more importantly, a leakdown test are in order. The leakdown test will give you a percentage rate of leakdown past the rings. It could be that the pistons/rings weren't clearanced properly or that the rings didn't "seat" for some reason. Also could indicate a cracked or broken ring from assembly that wasn't discovered at the time. Although baffled valve covers are better for preventing oil from blowing out of the breathers, if you didn't have this problem before the rebuild with these covers/breathers you shouldn't now.

Keep us posted
Tom

p.s. Problems with the piston and ring clearance could be:
* too great of clearance between the pistons and the cylinders.
*rings too narrow for the grooves causing ring flutter or rocking.
* too wide of a ring end gap.
*wrong honing pattern on the cylinder walls that is not campatible with the rings used.

Also keep in mind that excessive oil pressure saps horsepower. More than you would think. 60 psi (cold) 45 area (warm) is more than enough for any street engine.

 

[VettePaul]

Thanks Tom. I did a compression test tonight which went as follows:
1-134
2-130
3-135
4-134
5-145
6-132
7-145
8-130

What I did notice though was the spark plugs had "crusty" residue around the base of the prong which looked a bit on the black side. Could this be due to the running-in oil I've had in for the last 300 miles ?
Cheers, VettePaul.

 

[AKRAY4PLAY]

Paul,
you are running far too much oil pressure for your build. Lingfelter's says you can easily get away with 10 pounds oil for every 100 hp. 80 psi in a mild street motor is too much. Oil pressure is good, but when you put a big pump at high pressure, you start running the risk of pumping all of your oil to the top-end of your motor and starving the pump. I would confidently say that the extra oil spewing from the breather is an over-saturation of the rocker area. Your rockers are flinging oil out of the covers and the problem only gets worse the higher rpms you spin. if you have a 6 quart oil pan, try getting some baffled rocker covers. I think you will be alright if you get your consumption and leakage to minimum, and happier. As for the oil pressure, it is not optimum, but it is functional. Remember to carry a couple of extra quarts of oil until your motor quits lowering the level. GM performance has some real nice aluminum baffled rocker covers for about $100. As for the crusties on the plugs, it is most likely from burning oil, being sucked through the pcv line. best of luck, Brian

 

[wolf_walker]

It's always a good idea to impove oil drainback from the top end on any sort of rebuild. This entails a lot of close personal time with a grinder smoothing and enlarging the drainback holes in the block.

Good reading about oil pumps here..

http://www.melling.com/techbul1.html


A high preasure pump is not very well understood by most people.
Say you take a high mile motor that has 20psi of preasure on the highway, you say to yourself, alright, I'll stick a high preasure pump in there and it will have higher oil preasure, right? Wrong, you still have the same loose clearances and such that are allowing your stock pump to read so low, and that has not changed. All a high preasure pump has is a relief spring that opens at a higher preasure, but being that a pump dosent make preasure itself, it makes it by the resistance the rest of the motor offers, then there are no gains, because that loose motor and not very much resistance is still there.

Things get more interisting with a high VOLUME pump, this will pump more oil per revolution than a standard pump, therefore in the earlier mentioned wore out motor with 20psi, it will likely show some improvement, because there is a higher volume of oil being Pressed into the oil passeges, therefore the preasure goes up.

If your gonna get anything, get a high volume and preasure pump, and make darn sure the oil can find it's way back down to the pan so as to not empty it and cause problems.

That's my little oul pump tech rant, accurate as per oil pump designers and acording to my experience.

 

[VettePaul]

Thanks guys. I ordered some new edelbrock baffled valve covers yesterday. They should be with me today. Seems like a whole lot of work now to change the pump. In hindsight listening to you guys I wish I had just put a standard pump in. wolf_walker. The pump I have is a high volume/pressure one. I suppose that's a little +. Cheers Guys.

 

[wolf_walker]

Those baffeled covers should fix the problem. The only other thing I'd really ever woprry about is it pulling the pan dry if it's a high preasure/volume unit, especially on hard take'off's or in cornering at higher speeds. Unless you drive pretty hard all the time I imagine you'll be allright...

 

[VettePaul]

Cheers wolf_walker. That's put my mind at rest a bit. What about the compression readings, are they ok ? VettePaul.

 

[wolf_walker]

To be honest I don't remember what the target range is, but I do know that your highest is 145 and lowest is 130, and that's not bad enough that I'd worry about it. Anyone know what PSI he should be seeing here?

If you can arrange it a leak-down test would tell you absolutly if things are sealing as they should, but if I had to guess from here I'd say your alright.

 

[AKRAY4PLAY]

just guessing on the compression ratio of 8.5 or 9 to 1. you should be seeing around 145 to 150 psi. with all of the extra oil being flung from the cam onto the crank, crank to cylinderwalls, i would bet that you are over taxing the oil scraper rings on your pistons. this would keep the rings from seating and promote glazing of the cylinder walls. try running some real good race fuel (110 octane) mixed 50/50 with premium gas for your next tank full. the higher octane burns slower and more complete than regular fuel. it may help burn the exess oil off the walls and seat the rings, if that is indeed your problem. it can't hurt your motor, but race fuel is usually around 5 bucks a gallon. so for $35 you can have 10 gallons of good go go juice. how's your jetting?? if you are running way to rich, most of the symptoms are the same. crusty plugs, odd compression, poor performance, etc. a leak down test with a tail pipe sniffer test will narrow the paths to take. if the tail pipe is telling you to much fuel, lean her out until the plugs are a nice cream coffee color. most IM shops can sniff the mufflers and tell you how the jetting is. keep plugging away and you will get her whipped into shape in no time. brian

 

[VettePaul]

Thanks for getting back. Since this thread started I have made a couple of changes. It seems to have cured the problem. I changed the oil from running-in oil to Valvoline 20/50. Also bought some new Edelbrock Elite valve covers and installed the baffles where the breather is etc. Maybe it was just the thin oil but it seems to have cured. It's not covering the rear end in soot anymore either. I've been to the Corvette Nationals today which they have once a year here in the UK and on reaching home tonight have clocked a total 1500 miles since the rebuild. Maybe it's all starting to settle in now. Thanks for getting back and I will have another look at these compression figures..VettePaul.

 

[JHL]

Hi Paul,

nice to hear the car is ok, how was the show today. We decided to go to Tatton instead as my mate like to see a bit of everything. There were about a dozen Vettes turned up and the usual mix and match of other cars. Strangely there was a guy turned up with a ZR1 which he was trying to sell. I was going to point out that he was probably at the wrong day out. Notts Americana next weekend and I might even take the car.

J.