M20B25 Burning oil / High temps

[Terroth 5]

So today I finally got the new engine cranking and started up, which was a great success. But the feeling didn't last long.

I let the engine idle for 10 minutes and within that short space of time, it ran well, idled smoothly at around 600rpm, wasn't doing stupid sh*t till...

It appears to be burning oil within the engine bay. Primarily it is coming from around the exhaust manifold, and it is consistent, its not like I just accidentally spilled oil on the exhaust and it needed a minute to burn, it continued to burn and burn and burn as the engine idled, however there was no white / blue smoke coming from the exhaust.

The second issue is that it is running hot as f**k, as in within the 10 minutes of simply just idling, it didn't even make it to 10 minutes because it reached near red temps and i decided to turn it off. The heaters were set to full and were all cranking. The lower radiator hose was ice cold, yet the upper radiator hose and hoses leading into the thermostat were all bloody hot.

So what am i looking at here? I can provide videos or pictures if that will be any help as well. The last thing I'd like to hear is that its f**ked before i begin.

[Ahmedsinc 414]

Sounds like it could be a damaged rocker gasket & a blocked radiator / jammed thermostat / failed water pump. Is it a replacement engine you've installed or have you just done a HG replacement? A little more info would help

[Terroth 5]

Its a replacement engine I bought. I don't see any oil seeping out of the rocker cover gasket and its burning so much that it would surely be noticeable? The waterpump is new, just installed it when i did the cambelt. The thermostat was off of my other M20 engine that was working fine on that engine, but I suppose it wouldn't hurt to test it on the stove.

[Ahmedsinc 414]

What was the reason for the replacement?

Edit: Has the cooling system been correctly bled? I understand the M20s are particularly troublesome to get right

Edited January 11, 2016 by Ahmedsinc

[Terroth 5]

Previous engine snapped its cambelt. Going to try and bleed it correctly again.

[hotwire 352]

As far as temp - bound to be an air lock.

Oil burning - are you meaning there is a continuous supply of oil dropping onto the manifold/exhaust? You should surely be able to see where it is coming from.

Any residue on the exhaust will take quite a while to completely burn off - more than 10 mins

[Terroth 5]

The temperature was definitely an air lock, I just refilled it from each hose going into the thermostat and bled it, its not completely bled at this point but is currently running just a smidge past halfway. Ill go at it again tomorrow when it has cooled down again and i can top it up inbetween bleeding it.

I hadn't compensated for the fact that the block was completely drained before i refilled the coolant and only refilled it from the overflow, so there was likely a large f**king pocket of air in there that was giving me hell.

As for the burning oil, I'm still at a loss, I will take pictures of it tomorrow in daylight when it'll be easier to see whats going on. But from what i can tell, there is definitely no oil leaking from the valve gasket, although its difficult I can't really see it leaking from the back of the gasket either. I can't see any oil leaking from the filter / oil cooler inlet / outlet either, although I may need to see it tomorrow in a better light.

The engine had been sitting for over 6 months, although it started up rather quickly, with a few sputters and spits and began idling smooth as a whistle, sounded great apart from your typical M20 tick. The oil, after now doing the coolant and running the engine for over 15 minutes doesn't appear to be forming plumes of smoke, but I can smell / see the odd amount still popping up.

Perhaps because the engine has sat for so long is why there was some oil burning? Surely if the headgasket was on its way out the oil in the car would be turning milky, and perhaps even seeping out the side between the block and the head, but would that not be rather noticeable?

[Ahmedsinc 414]

If your head gasket failed that badly it wouldn't be burning on the exhaust manifolds. Mayo under the oil cap is typical but not always present. Look for a discoloured patch on the headers for clues as to the leak location. Sometimes it can be hard to spot under artificial lighting too. Is the oil loss bad enough to be noticeable on the dipstick?

[Ahmedsinc 414]

Sitting engines tend to collect oil in the cylinder bores, so will produce blue / greyish smoke on first start, smoke in the engine bay points to a failed gasket or cracked cover

[Terroth 5]

The headers seem to be their usual orangy brown color, although there are 1 or 2, some darker spots on the bottom, but having a feel that just seem to be patches of dirt rather than oil.

Ill give them a good clean tomorrow and give it another crack to properly locate the source of the smoke.

[Ahmedsinc 414]

Any updates?

[Terroth 5]

Cleaned it all up and it appears to be running fine, tiny bit of burnt oil initially but its been idling for 30+ minutes and hasn't been burning anymore, but I'll keep an eye on it to see if any wet patches come up.

As for cooling, have bled it successfully, actually might be running a bit too cool, sits outside blue just before the first marker, so might have to have a look at the thermostat.

Cheers for the help though, seems to be running well now. Just have to wait for the shifter parts to arrive, disappointing having it running and not being able to drive it.