Smokin' Joe Frazier - Burning oil

[Benny]

I'm having an issue with my new 1275. I fired the engine last week, and did the cam break-in. After that was done, I immediately took it for a drive to get a load on the engine to seat the rings. It runs very well, and is quite strong for a 1275. After putting about 30 miles on it, I had it idling in my driveway, and when I blipped the throttle, I noticed a big puff of thick blue smoke out the exhaust.

The head was a complete Metro head that I supplied to a very reputable machine shop for a basic check, service, and valve job. The compression is right around 155 psi, and is very consistent across all four cylinders. There is virtually nothing coming out of the crankcase breathers in the way of oil vapors, and the breather hoses are are REALLY dry. After 30-35 miles, the oil is still totally clear and bright green in color (Brad Penn brand is supposed to be green). All this leads me to believe the rings are seated pretty well.

I pulled off the intake manifold, and found small pools of brown oil in the manifold runners, and the intake ports on the head were wet with oil all the way down to the valves. I figured that perhaps I'd over-filled the dashpot (single HIF6), and maybe the engine was pulling dashpot oil. I cleaned it all up, and put the carb back on with just a little bit of dashpot oil this time around.

i took it for a blast around the local hills for about 6-7 miles, then took it down the motorway for about 5 miles. I would try to look behind me as often as possible, but couldn't see any smoke. I came off the motorway, and pulled the spark plugs, and they all looked great.....sort of a dark tan, and nice and dry.

I started it back up, and let it idle for about 30-45 seconds, then blipped the throttle, and POOOOF....big cloud of thick blue smoke. I dont think there is any way it can possibly still be burning dashpot oil. There is little to no smoke at idle, and none when under a sustained load as far as I can tell, but right off idle, it's terrible. The longer it idles, the worse it gets.

Any ideas what is going on? The head received valve stem seals on the intakes, but I have noticed when I pull the valve cover that the pockets are very deep around the valve springs on that Metro head, so there is a lot of pooled oil around the spring seats.

I'm out of ideas apart from pulling the head, and checking the valve stem seals and guide clearances......any ideas?

[JC T ONE]

How much work have been done to the head ?

I have seen heads that have been ported so much that hairline cracks appeard in the intake ports, and the engine did just like yours.

Reason is that the oil return from valve gear, goes to the sump, through the holes for the pushrods.


The reason it dont smoke while driving, is that the vacuum isnt as strong, as when idling.

[Benny]

Good question....no porting has been done to the head. It's just a standard Metro casting that was crack tested, cleaned up, valve job, new valve stem seals. I'll need to check my receipts to remember whether the guides were replaced, but they certainly should have been checked.

I'm really not get much (if any) smoke at idle. But it gets bad right as I come off a prolonged idle.

[JC T ONE]

Ahh I see, but cant see oil go upwards into the intake port ?

does it smoke on startup (from cold ? )

[Benny]

Yes, when I found the pools of oil in the intake manifold, I was sure I had determined the source of the oil to be the carburetor, but after reducing the amount of oil in the dashpot, and taking it for a long drive, I can no longer imagine that is the source. The first pic shows one of those pools after I wiped it with my finger....there was probably 3-4 times that amount of oil when I first pulled it off.

I would not say there is excessive smoke on start-up. When the engine idles for 30 seconds or so, and I bring the revs up, it smokes as the revs rise up, but clears up quickly if I hold it at something like 2-3k.

[JC T ONE]

So no valve guide seals on exhaust guides ? only on intake - or ?

[251 ENG]

Has the head been fitted with new guides ?

If so have they been pressed too far in to the head ?

[Spider]

How have you got the crank case breather(s) plumbed up?

[69k1100]

What type of fuel pump? If its mechanical could it be leaking oil into the fuel?

Edit : drmini from the aus mini forums has noticed that the flywheel breather can sometimes have oil "chucked up" the pipe and directly into the manifold.

[mk1]

From the description, I would also strongly suggest guides, however, I am struggling to imagine how this could put oil in the inlet tract.

M

[BRI MK1]

Are you sure its engine oil and are you using a servo it could be the servo sucking brake fluid up.

[mk1]

Good Thought!

M

[Spider]

Are you running with a PCV Valve?

Is it in good condition and working properly?

Or, have you got the breathers set up for the CCV system and plumbed to the Inlet Manifold, like you would for a PCV set up?

Also, are the Oil separators OK, still got gauze in them?

It would be easy to jump to the conclusion of valve guides but there's just way too much oil for that.

[Benny]

Thanks for all the suggestions, I'll try to answer all the questions.

The only thing plumbed to the carb is fuel. There is no PCV, and no brake booster. I have the late-model vent on the drop-gear housing, and a large vent on the valve cover. Those are both plumbed to a "catch can" mounted on the inner fender, and the catch can is vented to atmosphere at ground level. The vent lines are totally dry, and if I disconnect them while running, there is virtually nothing blowing from them.

When I found the oil in the inlet runners, I was convinced it was NOT engine engine oil. The oil in my engine is a bright green color (similar to anti-freeze), and this was relatively clean, and brown in color. This was why brain immediately went to the dashpot oil.

I believe the guides were replaced, but I will need to double-check that. The head was done by a shop that specializes in British engines, exclusively.

I'm running an electric fuel pump.

[mk1]

Benny, In view of the above, I hind it hard to imagine that it could be anything but the guides, either not having been replaced, having been replaced & over reamed or having been pushed too far into the head. It could of course be a combination of all 3. Whatever you do, I suspect that the head will have to come off at some point.

I would suggest that your next step should be to contact the people who did your cylinder head, being "specialists" It would be perfectly normal for you to to see if they can "suggest" what the problem is.

Mark F

[Benny]

Thanks Mark,

I was in the process of pulling the head last weekend when I discovered the oil in the intake. While I'm still relatively confident this is not a rings issue, I'm considering doing a leak-down check this weekend, to see if that tells me anything about the rings. Following that, I'll likely be pulling the head.

[mk1]

Good luck Benny, I'll keep my fingers crossed that your ring are fine & it is a "nice easy" cylinder head issue.

M

[underkut]

Have you checked the little valve on the rocker shaft is not allowing too much oil to the top end?
This could account for things if the guides or seals cant hold it back.
Does not account for the oil colour though

[Benny]

I'm not aware of a "valve" on the rocker assembly. The oil feeds to the rocker shaft through the forward pedestal, and flow into the rocker box is "metered" by the clearance between the rocker bushings and shaft. I'm not aware of a way to limit this flow?

As I mentioned in a previous post, I do find it surprising how much oil pools around the valve sprin seats. There are drainage passages that run to the pushrod holes, but they don't seem to drain very effectively.

[underkut]

Benny
On your rocker pillar that feeds the oil up the pedestal you should have (unless they changed it) a different top with a slot in ,the slot holds a threaded screw that restricts or controls the amount of oil entering the rocker shaft.
If this screw is a few to many turns out it can allow too much oil.
I had it on an old rebuilt head years ago.
Annoyingly my dad spotted it straight away (as was normal )