Wrecked Cylinder Head :(

[PaulC]

I had the car out today and it was running great. Flat out it was screaming didn't seem to be lean or rich.

But after nearly a full tank of flat out passes it started to lose power, then cut out just as it stopped at my feet.

It normally has a lot of steam flowing off it in the wet grass, but I could tell this wasn't steam. It was grey oily smoke and it stank of burning engine.

Overheated. Luckily the piston was free and not bothered by this. The glow plug was blown, but a new one got it to start and run fine again. I richened it did some flat out passes, took the temp, 148*C, so I richened it again, oddly it seemed to go even faster, and made a good amount of smoke doing it. Head temp was then 110*, much better.

I expected too lean to cut out, stutter or stall frequently, but it sounded fine. I seems it was nearly 1/2 a turn lean

But I flooded it when starting after a refill and putting the plug back in, it seemed to resist just a little, not much, I thought it was just the gasket catching in the threads and spun the plug down. Then looked. Plug wasn't straight.

So obviouslly it wouldn't start again. Took it home and there were slithers of thread peeling off the plug hole. So, the threads are stripped on the cylinder head. I suspect the overheating would have weakened them badly as I wasn't using any torque on the plug wrench at all when they cross threaded.

So... Now I have to find the part number for the cynlinder head and email the manufacturer to see where I can order one from

So, buggy off the road for a few weeks no doubt.

Paul

 

[PaulC]

Turn out it's just the "head button" or "combustion space" as the german's call it. £20. Found a UK online shop with them.

Should be easy sorted.

Anyone wanna start taking bets on what I'll break next?

I'm excluding the cracked body shell that will only get worse...

I'm placing bets on diff casings or the front hub carriers again.

 

[2revo1maxx]

I had the car out today and it was running great. Flat out it was screaming didn't seem to be lean or rich.

But after nearly a full tank of flat out passes it started to lose power, then cut out just as it stopped at my feet.

It normally has a lot of steam flowing off it in the wet grass, but I could tell this wasn't steam. It was grey oily smoke and it stank of burning engine.

Overheated. Luckily the piston was free and not bothered by this. The glow plug was blown, but a new one got it to start and run fine again. I richened it did some flat out passes, took the temp, 148*C, so I richened it again, oddly it seemed to go even faster, and made a good amount of smoke doing it. Head temp was then 110*, much better.

I expected too lean to cut out, stutter or stall frequently, but it sounded fine. I seems it was nearly 1/2 a turn lean

But I flooded it when starting after a refill and putting the plug back in, it seemed to resist just a little, not much, I thought it was just the gasket catching in the threads and spun the plug down. Then looked. Plug wasn't straight.

So obviouslly it wouldn't start again. Took it home and there were slithers of thread peeling off the plug hole. So, the threads are stripped on the cylinder head. I suspect the overheating would have weakened them badly as I wasn't using any torque on the plug wrench at all when they cross threaded.

So... Now I have to find the part number for the cynlinder head and email the manufacturer to see where I can order one from

So, buggy off the road for a few weeks no doubt.

Paul

That's a bummer. You say grey oily smoke? Or grey oily stuff. Grey oily anything is bad. It usually means an excessive amount of wear happened somewhere in the engine.:whhooo:

 

[PaulC]

That's a bummer. You say grey oily smoke? Or grey oily stuff. Grey oily anything is bad. It usually means an excessive amount of wear happened somewhere in the engine.:whhooo:

Grey oily smoke. Maybe more blue and smelt of burning oil and engine, hot metal. I'm hoping just the oil on the engine (after run, evaporated fuel, factory mold lube) burning off. I'd seen similar smoke after I sprayed it with protectant oil, the block burnt it off within minutes the heat sync didn't, but ... having the heat sink that hot is not a good sign.

There is a chance the plug wasn't perfectly tight and it was leaking exhaust gas. I donno. Engine ran fine after it, when it cooled down, until I crossed the plug threads