I recently replaced my pcv system with breathers, because I thought they would help the crankcase stay ventilated easier. The pressure was so much that oil was getting past the valve covers and even out of the dipstick tube. After changing to breathers the oil seappage has stopped, but now there's another annoying problem. After the engine warms up to temp there is quite a bit vapor coming out of both of the breathers. At idle there isn't much, but the amount of smoke increases a bunch when the engine is revved up. The higher the engine is revved the more smoke comes out. I'm using factory spec cast rings that are supposed to seal quicker than moly ones. Is 600 miles enough time for these rings to seal properly?
One more thing, when the car was first ran the timing was wayyy advanced, which I'm hoping didn't damage some of the rings. I'm talking 30-40 degs. base timing. The engine would ping like crazy with only half throttle. I'll be doing a compression test within a week to know for sure. I'm just wondering about the blow by.

 

What was the end-gap of the new rings when you measured them in the bores?

 

The top ones had about .018 clearance and the second ones had around .014 clearance or close to it.

 

Ok then, time to do compression and leakdown test to see what's going on in each cyl.

 

I just talked to my friend who pulled/put in the engine who is a good and really fast working mechanic. He said that with the amount of smoke coming out of the breathers the rings more than the valves are probably messed up. We are going to do the compression test on Wed. and I'll post the results for you guys. I wish I would have had this guy do the bottom end in the first place. This will be the second time the engine has to come out due to lack of quality work from me and my dad. Then again this is my first engine rebuild and really don't know a whole lot about jacksh$t.

 

What kind of engine oil did you use for break-in?

 

Regular old 10W40 Kendall dinojuice.

 

Anybody else have any thoughts about the smoke/vapor coming from the breathers? I'm not going to be able to get the compression test done for a few days still.

 

Leakdown will be the more conclusive test. Basically you're pressurizing your crankcase abnormally, and the common source of pressure is rings not sealing.

You can pull the spark plugs and compare them against each other, one or more will likely be oiled up if it's a ring issue...they leak combustion pressure only under compression, whereas under vacuum they'll pull oil in from the crankcase.

 

I've pulled 6 of the 8 plugs, I couldn't get to #'s 6 and 8 because my starter heat shield gets in the way. That's why I'm waiting on my friends lift to get freed up. None of the six plugs I looked at had any oil residue, if anything they showed signs of the engine running a little lean. The way we were going to do the "poor man's" leakdown test was taking all the plugs out, checking each cylinder three times, then repeat while squirting a teaspoon of oil in each cylinder to see if compression rises. Then after I see the results I may or will for sure look into doing an accurate leakdown test. By the way Kevin, have you heard of engines with good compression that have quite a bit of smoke coming from the breathers? That's the main question I'm asking and no one seems to have answered it yet.

 

I've seen one engine that passed compression easily (190psi +/-5psi) and had cyl walls so scored up you could, well, I don't have a metaphor right now but they were scored up badly.

It was oiling down two plugs badly, fouling them up after just a few runs pulling water skiers. We slapped on the leakdown tester and found the culprits right away.

In your case it's just a matter of ruling things out one at a time until you hit the root cause.

 

Check this out concerning ring end gaps. Scroll down close to the bottom of the page and start reading where it says "RING END GAP RECOMMENDATION GUIDE" and read the "Notice" paragraph:
http://www.federal-mogul.com/cda/con...5_8682,00.html

hmm.......

 

Guys I did a compression test a couple weeks ago and ever cylinder tested 189psi +/- 1 or 2 psi. I did this with the engine hot. None of the plugs are oil or fuel fouled. They actually look like the engine is running a little lean. I burn no oil and the engine does not have as much power as it should. I'm having a friend intall a new walbro fuel pump this week, we think that the stock one is weak, because when checking idle pressure, the gauge rapidly fluctuates between 40-45psi. I know I need to do a leakdown test cause a compression test doesn't mean jack when you looking for a blow-by problem, right? The engine has about 900 miles now and it still has a lot of white steam coming out of the breathers, especially when you rev it up.

 

Are you reuseing your stock heads?? I personally think you've got more of a valve guide problem.... My old 305 didn't burn oil but I had oil vapor like crazy outta the valve covers. I also know that 305's had bad valve guides, so.... Do the leakdown check and double check the rings are good. An take it easy on the motor for now. Run another few hundred miles or so, change the oil, check the timing, and run with the best. If it turns out the guides are bad, just pull them and have the machine shop put new guides in, an while you're at it have 'em put 2.02/1.60 valves and do a good port job. It's worth the money IMO. Just my .02 and best of luck.

Chris

 

KB Pistons need a lot more than .018 top clearance. You may have damaged the rings.

 

They dont need alot more but see this link!
http://www.kb-silvolite.com/speclear.htm#CHART
According to their site top ring end gap should be around .026

 

man i feel your pain. i had the EXACT same problem in my iroc when i first got the new motor going. eventually i found that i had collapsed all of my lifters, and this will really make your motor a real bug sprayer. id look at the valve-train before i thought about pulling the motor. pull off your intake and look down at your valves. if you see puddles of oil on your valves, its not rings. its either bad intake gasket or bad valve seals

 

If he is using kb pistons his top gap should be more then 18,kb pistons are known for taking the top ring land off with tight clearances.4.030 bore x .0065 = this is the formula he should be using which means a 26 top gap at least,if he was detonating like he said it couldve done damage..Ive run as high as 34 top gap on some circle track motors ive built Have you found out anymore yet?

 

Sorry to jump off subject but, Nitrovette....Sweet juice setup. Same way I'll do it as soon as I get the ***** for it.

Chris

 

Jacked up like a mother and ready to kill some rustnags!!

 

Hey dude, there's nothing wrong with your engine. The V in PCV is for ventilation. Since you removed it and installed breathers, the engine is simply venting the excess internal thermal pressure through the breathers. Re-connect the PCV system, problem cured !!!!!!!

 

Thanks man, that's what I've been waiting for someone to say all along. I think part of my problem with the car not running like it should was a weak stock fuel pump, which was just exchanged for a high-flow walbro today. I'll have the car tomorrow and see if it seems any faster. I'm going to have a friend tune my setup for part-throttle later this week. Then I'll be heading for the dyno for WOT tuning with a wide-band 02. Then I'll know for sure if I need to do a leakdown test, because I should have 300-320+rwhp. If I don't I'm gonna be OPOMF.

 

Joe,

Using a breather-type oil filler cap is almost never a good idea on a MAF system. The air drawn into the breather eventually becomes part of the fuel charge mixture, and therefore needs to be measured by the MAF. That's why the OEM setup used a breather tube from the TB to the rocker cover.

As for crankcase pressure and ring leakage, you can use the hose from your compression tester to connect a leakage tester and get a better idea of possible leakage than a regular compression test might rebeal. Run over to your favorite hardware store (a real one, not Home Depot) and get some brass fittings, a couple of 0-100 PSI gauges, and a pressure regulator. You may need to pick up a 1mm (0.040") drill while you're there if you don't already have one.



That controlled orifice is a plug soldered in the hex nipple with a 1mm hole drilled through it. Set the inlet pressure to 100 PSI, and connect the outlet to your cylinder via your test hose. The difference in pressure will be the percentage of cylinder leakage. Setting the inlet at 100 PSI makes teh calculations easy. 100 PSI in and 85 PSI on the test gauge indicates 15% leakage. It's that simple.

 

Thanks for the reply, Vader. I seem to understand the concept somewhat, it's the details that I'm not getting about making a leakdown tester. Do I use one gauge to tell how much air is going in and do I keep the other at zero through use of the regulator, until the air is pumped in accordingly? Then do I somehow turn the other gauge that reads zero on so it will tell me how much air comes out? I guess this is what you're talking about, it's just that I'm not familiar with assembeling custom tools like this. What I need are detailed step-by-step instructions on the process of making and using this gauge. I know this probably sounds stupid, but I'm just not understanding the picture either.

This car is driving me crazier by the day, I'm about to just pull the engine apart for the 3rd time in six months, because I'm almost certain from talking to different car guys that the rings are shot from severe detonation that occured in the first few hundred miles. Does anyone else have opinions about severe blowby in my case. Remember, when I was running a pcv system, the crankcase pressure would blow the dipstick out of the tube, and oil would blow out of the valve covers onto the headers, and oil would also blow out of the pcv grommets. There's no way in hell that this should be happening with a 1200 mile new engine.

 

this may or may not help you.

When i first built my motor (carbed) there was smoke coming from the breathers.

Leakdown test showed 10% on nearly all cylinders!! this with less than 1000 miles. My ring gaps were TOP .028 Second: .025 (for blower)

I pulled the motor again for a different reasons, pulled the heads.
I found the head gasket had blown and coolant was somhow making its way to the lifter valley, where it was reaching boiling point and evaporating out. i found evidence of this in the valve covers and all over the place where it had condensed and caused things to get milky. especially in the oil pan. but i wasnt burning it....

then i found another strage leak factor. i had the PCV hooked to my exhaust to use exhaust to pull the crank case vapors out. it works so well, it was pulling oil out of the valve covers. the oil would then proceed into my headers down LOW Enough so it would burn but not completelly. it would then collect in my Y-pipe and leak out a tiny hole causing me to see oil under the car all the time, and it would smoke off the Y-pipe as it dripped out causing a cloud of smoke to flow into the car and always around the motor making me think oil was always burning somwhere.

stranger things have happened. if oil is shooting out the dipstick it doesnt mean its from pressure in the crank case. one time oil came shooting out of my dipstick but i realized it was coming from around the dipstick hole, not directly out of the dipstick. when i first built the motor i forgot to put IN the dipstick, and oil was squirting out of there like nothing i have ever seen. did the same thing to the tranny detent cable hole, left it uncovered. massive fluid spill.

oil always comes out of my valve covers at WOT. it always smoke right off the headers though, normal engine behaviour for me.