Cooked RV8?

[garrycol]

I have a rebuilt top hatted 4.6 RV8 with carbs that has virtually no kms and still has the running in oil still in it .

In September last year I wanted to check a few things with the engine hot and the thermostat housing stayed cold and the thermostat did not open and the engine got hot.

I have started the engine a few times since without getting it hot and all was OK. I changed the thermostat this weekend and ran it yesterday and all was good – got up to normal operating temp again with no issues.

Today I started the engine up and really heavy white/blue smoke came out of the exhaust – so thick it was smoking out the neighbourhood. I didn’t get any pics but later I went out and restarted to get something – this time the smoke was no where near as thick but is still there. Here is the vid (click of the pic to open).
VID_20200412_163943

So it looks like when it got hot last year I did something to the engine that has not manifested itself until now.

Oil is nice and clear, coolant does not have any bubbles or oil.

Heavy thick black oil is coming out from exhaust pipe joints on both banks of the engine.

My thoughts are that with the engine getting hot – there is at a minimum a ring issue – clearly oil is being burned. When I have had similar symptoms in other engines in the past, broken/melted rings have been the cause.

At this stage I am thinking of pulling the 4.6 and putting the old 3.5 back in so that at least I can use the vehicle and sort the 4.6 out on the engine stand in slow time.

Happy to take ideas and/or thoughts.

Thanks

Garry

[DaveEFI]

If it is sounding OK, I'd be inclined to use it normally for a while, to allow things to bed it. Assuming it's not actually consuming coolant - can you do a cooling system pressure check? Of course using it normally may not be possible at the moment.

[Ian Anderson]

What engine was in it before and was it pouring out oil?
If so now you have run this to temperature are you just blowing it out of the exhaust pipes?

Have a look at the plugs.
Are they all oily or just one or two?

Could be a valve stem seal failed and allowing oil to pour in.

That would be my first thing to check.


Ian

[stevieturbo]

What does "the engine got hot" mean ?

How hot ?

It'd take something special to do harm in terms of cooling system just sitting ticking over.

[garrycol]

I am changing the oil from the running in oil it has at the moment to normal oil and will drive it around the block a few times and get it to operating temp and see what happens.

The previous engine was a 3.5 Rv8 that was in good condition.

When it got hot last year (Sep) it was parked and coolant boiled. No obvious issues since but it has not been driven since - just started about once per month. Ran it on Easter Saturday until it was warm - 85/90c and sat there running ok at that temp. Then shut down.

Started Easter Sunday afternoon and thick smoke billowed out from start. Today neighbours mentioned how it was smokey when running yesterday.

Started it today an moved it to the drive to change oil and filter.

If it is still smokey after the drive - then looking at plugs (noting both banks are smokey) and then off with the rocker covers.

There is no coolant loss.

Cheers

Garry

[garrycol]

Well started up this morning and smoke everywhere. Went for a drive in my local area. This was the result driving up a hill. (click on the pic for the vid)
Vid Uphill with Smoke

Very disappointing but then did a loop back around to do another run up the hill and - no smoke (click on the pic for the vid)
Vid Uphill no Smoke

So I am not so sure but definitely not a cooked engine

I guess the likely culprit, as has been suggested, are the valve stem seals.

Cheers

Garry

[DaveEFI]

OK. So not going to bed in. I'd say that smoke more than no valve seals at all. They often disappear on older engines.

Simple thing to check is the crankcase breather. If that is blocked, you will get lots of smoke. If it's fine, and the oil level isn't vastly over, I'd say you have major piston/rings problems.

[garrycol]

Thanks for those thoughts Dave. Basic engine and heads are all new/reconditioned - valve seals are new so should not have failed but of course not to say they have not.

So this morning the vehicle was parked in the drive in a different spot that it is normally parked. Started first go (cold) and no smoke and drove 20km to my garage to get a safety certificate for the LPG system. Ran fine, no smoke at all - so now no smoke when cold or hot.

So it seems all is good now.

Where the vehicle is normally parked it is on a slight sideways slope. I suspect oil had pooled in the low points up in the rocker covers and with the engine cold the oil had run down into the combustion chambers - valve seals should have stopped this though. Once cleared this problem has not reoccurred and engine is not burning even a little oil, so the valve seals must be OK.

Garry

[DaveEFI]

Very odd. If oil lying in the heads was the problem, you'd have expected others to have experienced it. As I said, I've had old engines where the oil seals have totally disappeared but didn't do that. But the good news is if it can run without smoking, it can't be something serious like piston trouble.
My daily is a Porsche flat 6. They are notorious for occasionally producing clouds of oil smoke on a cold start, which clears quickly. But not every time. And never had a satisfactory (to me) explanation. My own experience says it depend how the car is parked up on a slope.
Mine is parked on the road which has a slight slope. And of course a camber either side. It never ever smokes when parked outside my house facing the normal way, but has done when not. My previous one did the same - both low miles and well maintained.

[garrycol]

Dave - thanks for the comments - yes seems all OK now.

Re your Porche - I also drive a Haflinger which is also a boxer engine but a flat twin. I also have to park it on a sideways slope and when it starts it always has smoke - the reason is that when parked with the engine oil hot, it is thin enough to slowly get past the stopped rings - not a lot but enough to smoke on start - bit not if the vehicle is parked level as the small amount oil on the bottom of the piston flows back to the sump but when parked on the hill this little amount of oil flows into the combustion chamber. Doesn't happen on upright engines but does on flat engines - did it on my Subaru as well.

Cheers

Garry

[DaveEFI]

It's quite funny reading the various Boxster groups - who seem far more up on the best polish to use than anything mechanical. Most say the oil separator needs replacing. Only a few seem to know boxer engines are prone to it on occasion. Given the engine is sort of symmetrical, not quite sure why the road camber seems to make a difference. Pointing either way up a slope I can understand.

Getting back to your problem, are the oil drains from head top back to block clear? You'd need a lot of oil lying there to get to the valve stems, past them, and burned. And have you checked there is a slight vacuum in the crankcase, engine running? You should be able to feel it by removing the filler cap.