Some of you may remember a couple of months ago I had an incident wherby I hit my sump on a kerb, breaking engine mounts etc.

Well got engine out, separated crankcase to sort a gearbox issue whilst it was out (replaced 2 cogs after waiting a month for the parts!). Got engine mount and chassis welded. Engine back in last week, started and sounded to be running lovely. Was well chuffed since this was the first time I'd done anything remotely technical on an engine.

Fastened prop, wiring and everything else up this weekend. Tested engine and gearbox whilst on axle stands, again running lovely.

So out on first road test, and within a mile big pile of steam! No sign of leakage from radiator or hoses, but liquid dripping from exhaust ports. So it looks like the head gasket's gone Can only assume that the initial knock must have stressed the join since the head and crankcase are mounted separately to the chassis. That bit of load must have been the last straw

Oil isn't really milky and coolant not particularly oily, but I'm guessing thats because I haven't let it run for long in that condition. However it's now not firing at all on cylinder one - presumably because the gasket means theres no compression. That coupled with the fluid from the exhaust port I can't think of anything else it could be.

Back to square one! At least I've wasted 3 cover gaskets and 30 quidsworth of oil for 1 miles running!

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Originally posted by gingerprince


So out on first road test, and within a mile big pile of steam! No sign of leakage from radiator or hoses, but liquid dripping from exhaust ports. So it looks like the head gasket's gone Can only assume that the initial knock must have stressed the join since the head and crankcase are mounted separately to the chassis.

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Originally posted by 02GF74
you can expect condensation to build up but it should go away once everything has warmed up; not sure if a mile is enough for that.

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Originally posted by gingerprince
Can only assume that the initial knock must have stressed the join since the head and crankcase are mounted separately to the chassis. That bit of load must have been the last straw

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Originally posted by gingerprince
I have a friend with a compression tester I can borrow so will do that (though it'll have to be a cold test - I'm sure running the engine on 3 cylinders with the other just bein delubed with petrol isn't a good idea!)

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Hi Si,

Sorry to hear of your bad news... hope you get it sorted soon and cheaply!

Well done sorting it for yourself... always admire the gifted!!!

All the best - Steve

Hmm OK, a little diagnostic help here please?

I borrowed a compression tester tonight and did a cold dry test on all four cylinders. Whilst they were low (around 115psi) they were all within the same ball-park. For now I'm discounting the fact that they're lower than book (171psi at running temp) because it's cold so the rings won't have expanded, and I think my clearances need adjusting too.

So, I'm now wondering why cylinder 1 isn't firing given it has the same compression as the others - partially discounting a gasket leak/case crack around that cylinder, no?

So, I've checked the spark for that cylinder and it's definately sparking.

It's definately getting fuel. After not too many seconds carb number 1 seems to overflow and I get fuel spurting out of the air vent pipe. When I subsequently remove the plug and turn the engine over the remaining fuel in the cylinder is poofed out.

I don't know how fast fuel should be flowing at idle - if a cylinder isn't firing is a few seconds enough for this to happen?

If not, then is it possible that something else is amis, for example the carb is dumping too much fuel in that cylinder or theres no air for some reason, and that my "fluid" leak was actually unburnt fuel?

What can I check next?

One thing I was hoping to do was cut off the fuel to the 1st cylinder (no injection so can't just unplug injector!) and run it to temperature, see if there's evidence of coolant leak and also do a proper compression test on the other 3 cylinders. I tried removing the vacuum piston and putting my finger over the main jet but there still seemed to be fuel presumably from idle jets, and again I got overflow after a short while.

Ideas anyone?

Thanks, Simon

[Edited on 27/8/08 by gingerprince]

It sounds like a sticking float in no.1 carb. Take of the carbs and keep them level, remove the float bowl of no.1 carb and see if the float is stuck down. If not, you may have a bit of muck in the needle valve (the valve that attaches to the float to control the fuel entering the float chamber).
If the carb is flooding (which is sounds to be doing) this will cause excssive fuel to enter the cylinder and will cause a misfire.

Cheers. I'll have a look at the float tonight see what's what.

It might still be secondary to another issue, but until I can fix that and run it up hot I'll never know.

Well, took float cover off tonight. No obvious sign the float was stuck, nor any obvious visible grit where the needle goes but I guess removing carbs could have dislodged something. So, whilst there I dismantled and cleaned all 4 carbs. Put back together and it's now running on all four cylinders so it looks like there was something amiss in the carbs

Ran it up to temperature (water to 90 degrees or so) on the driveway, still ran fine. Bit of smoke from the exhaust whilst the oil I'd lubricated the cylinder with burned off but otherwise okay.

So I wonder (nay hope) if some of the liquid expelled was condensation in the carbs from the word go, and only made its way through once I was on the road and the thing was under load?

Compression test when hot still isn't great, about 130psi so I may still have rings or valve seating issues but I can live with that for now. I'll worry more about that after I've sorted valve clearances.

So next test is another road test this weekend. Probably up and down my road to annoy the neighbours but make sure I'm not far away if it does still have a head gasket issue.

Fingers crossed it was just carb gunk! Not counting my chickens just yet but at least I'm in a better situation than this time yesterday!

And thanks for the carb tips

Grand, and you're welcome!