Anybody got any ideas?

The 200 in my Mav has an oil consumption problem. The motor has been completely rebuilt from top to bottom. The guy who had it before me drove it after the rebuild for a while but noticed that the engine was consuming oil and the plugs would become fouled after about a week of driving. He replaced all the rings a second time but found that the oil consumption problem persisted. I thought that maybe the problem was valve seals so I just pulled the valve cover and inspected everything. It all looks great, so I'm stumped. Anybody got any ideas?

Here is a summary of the problems:
Oil consumption (about half a litre to a litre a week), plugs become fouled after about a week of driving daily, no noticeable smoke coming out of the exhaust.

Thanks,

Saul

 

saul, it sounds like valve guides to me. does it smoke when you first start it?

 

It depends on who assembled your motor. An oil ring that is either cracked or put on upside down will cause the problems you are describing, even on a brand new engine. It's just a thought, and i hope that it's not the problem...but hey, it could be worse!

 

Thats the weird part, I don't notice any smoke at all. The guy who rents my basement suite is a mechanic (handy, eh? ) He figures that the motor might not have been broken in properly, and that once I drive it for a while it will be fine.

You are right though, it definitely could be worse. In the grand scheme of things this isn't a serious problem.

 

better do a compression test .

 

Oil

I think 71Gold is on target, if they did not renew the guides but put new seals on, then probably would not smoke on start up. Would however allow some oil to seep down the valve stem while running and could cause your probs. Have also seen the use of chrome rings in a used and honed cyl. never seal correctly, but they would usually smoke like crazy. At one time we used to put BaBo(aka Comet cleanser) in the plug hole to seat them in quick. Those were the days huh?

 

Similar to me

My 302 fresh rebuild sometimes smokes around 100 mph. I don't think that it is finished breaking in though. Have had it to 130+mph and it wasn't smoking then though. So I just keep it below 100 and don't worry about it. Oh - BTW my rings are Chrome moly, and the motor is 40 over and like Old Guy said, when the walls are honed, it is not perfectly smooth, but it's smooth. That could be it. I'm still learning though. Luck to you- Country Mav

 

Uh, Country Mav, you're done breaking that motor in, right? I hope you didn't just take it out of the machine shop at run it right up to 100 mph! Either way i think you're insane for taking it up to 130, mine starts to lift off after 100!

 

Here is a little more info that might help. I pulled all the plugs, they all have a slight film of oil on them, except the #3 plug which had oil literally dripping off.

Thanks,
Saul

 

There must be some smoke if there is oil all over the sparkplugs .

Oil rings ?

valve guides seals ?

PCV valve ?

cracked intake ?

 

Flog it!!

Try taking it out and running it hard...from a stop, floor it and keep it there, dont red line it. Dont use the brakes and decelerate hard. Do this a few times and you will probably seat the rings well enough to fix some of the oil consumption problems. If the valve stem seals are in good condition this may fix it. I have had this problem on a few cars and running them hard has fixed the problem in 3 of 4 motors. One 5.0 was using 1 quart per 100 miles...after, 1 quart in 3000 miles. This is just a guess but if the motor is new and rings were never seated this will help. ...Ok...everyone, am I crazy or not??

 

I've never had any problems with chrome moly rings or cast rings if there was ANY crosshatch put on the cylinders . I had one engine that had problems with chrome rings but that was years ago .

But .......... if you think the rings are not seated properly then accelerating hard ( more than 3/4 throttle ) thru the gears , but not over 4500 rpm or so will probably go a long way towards seating them if they are going to seat now .Do this in a safe place like a highway 5 to 10 times .

 

Ask the guy who did the job how he spaced the rings on the pistons before installing. If they were not spaced at the correct points and lined up, oil control will be a big problem.
If all the plugs are oil fouled It seems that something like this would be the problem common to all cylinders.
Also make sure there is not some source of oil being drawn into the engne through a hose from the crank case.
There are a number of ways to get to the bottom of the problem.
Vacuum checks, compression checks, excessive crankcase pressure and a little common sense thinking.
Most engines that have just had rings on glaze broken cylinders take longer to seat and hardly ever result in as good a seal as on new bores. We have found many times that breaking in an engine works the best using straight weight cheap oil for a couple thousand miles then change over to good oil. Reason is the good oils are too good when it comes to mating rings to cylinders for seal and result is a long time for total breakin. Not to mention the use of exotic ring types to add to it.
On factory new cars the oil is often a special mix for the breakin peroid for this reason. Slowly this is being done less because there is a new laser cylinder final finish that is starting to be used and results in a finish so good that we can't get close to with a regular honeing job.