conking out.

[roxylass]

eng no esc 181 hh1.
running in the test tank today water a couple of inches above the bottom of the exhaust tube put it into gear she conked out runs like a sewing machine out of gear,
each time i put her into gear she just dies out.
put her in the tank with the prop off into gear runs no problem im talking about a 6ft test tank by 4ft wide not like she is confined for space.

[Horsley-Anarak]

Will not run under load.

I would check the compression first.

H-A

[roxylass]

compression tester just arrived will test tomorrow.

[roxylass]

tried the compression tester today no reading at all gave it three good pulls, i have put a new cyclinder head gasket on.
it was going great till i took the head off to clean the water ways.

[Horsley-Anarak]

When you replaced the head gasket did you replace the head bolts with new Stainless Steel ones ?

Gaffers did that on his Century and the bolts did not tighten down correctly because of corrosion in the cylinder threads.

I would take the head off and clean the threads out with a 5/16" BSF tap and then bolt it all back together again
with a little jointing compound on the gasket.

Did you check the condition of the cylinder to head mating surfaces? They might need a light skim.

H-A

[chris]

just curious, did you keep the revs up a bit when you put it in gear, I remember one person who had problems, It turned out the way he had his drum set up when he put it in gear the propeller hit the bottom and stopped, he was very embarrassed when it was pointed out to him
Does the head gasket need sealant as I have found that they tend to seal themselves up after about half hour running, I haven't use a new head gasket, just the old one cleaned up, I always replace the head bolts with waterproof grease on the threads, so far I have been lucky with head bolts, I have only broken one.

[roxylass]

the compression checker i have when you look at the dial on the right hand side there is a screw half way up with a piece of fishing gut,attached to it is a small ignot of lead a little bit smaller than a 5p piece does this have to be removed, sorry i cant put a pic up but i can send a pic to a mobile if i have the number.

[Horsley-Anarak]

fishing gut, small ignot of lead

The mind boggles.

Mine just has a little pressure gauge and a bit of hose with a thread on the end.

H-A

[skyetoyman]

I can only assume is an anti tamper device to stop any exteral adjustment

[roxylass]

hi.
managed to find it.
if you google amtech auto compression tester you get a good clear picture picture of what i am trying to explain.

[Horsley-Anarak]

It looks like a calibration seal, don’t remove it.

That tester looks like it should do the trick.

Did you replace the head bolts with new ones ?

H-A

[Oyster 49]

I took my SJP on the canal last night, and it seems to be suffering from the same problem. Runs fine and starts first time, ticks over smoothly and revs. However once in gear it will not rev up and feels a little "lumpy". I will check the carb first, but I did notice a weep from the base gasket. Could that be the problem? Will strip it down for a look see. This is a SJP with clutched bottom end. 40 plus prop fitted.

[Charles uk]

There's the problem a 2.5:1 gearbox with a prop for a 3.5:1 box, which was designed by Seagull to turn with that powerhead at full throttle at around 1140 revs, whereas with the clutched gearbox at full throttle it will have to turn the same prop at 1600 revs something it doesn't have the power to do.

If you fit the correct prop I think you'll find it will get up 3800 to 4000 revs on the right sized boat.

As for the weep on the crankcase seal, tighten up the crankcase retaining bolts to spanner tight, if it still weeps a little leave it until the next time you have to service the motor, then fit a new base gasket.

To do this remove the carb & gas tank, remove the 2 powerhead retaining 5/16" nuts from top of driveshaft tube & lift off the powerhead, remove the 2 cylinder / crankscase bolts & remove the cylinder, clean both the gasket faces, coat cylinder base with a layer of RTV silicon & place gasket in position, ensure no RTV is on the crankcase side of the gasket, replace cylinder & lightly tighten in position, leave 24 hours & remove cylinder again, peel of all the boagies of RTV that have been squeezed into the transfer port & replace cylinder & firmly tighten.

I never use silicon on both sides of this gasket as it has never proven necessary & you don't spend a lot of money on replacing paper gaskets, this gasket only has to hold back around 4 lbs of crankcase pressure & provide a thermal barrier between the cylinder & the crankcase.

That's as long as the crankcase face hasn't had a battering.

[Oyster 49]

Hello Charles, thanks for the guidance. I checked the head bolts last night to find them only nipped up. There was a lot of evidence of oil under the gasket also. I've cleaned it up, cleaned out the waterways a little and reassembled with a unused gasket I happened to have. Just need to retorque it down. Looking closely at the base gasket that does not seem to be leaking, and the bolts are tight. I'll give the carb the once over also.

As for the prop, I also have an FPC with weedless prop, should I try that prop instead? Pictures below.

A bit of education for me here.

[Charles uk]

That's the right prop for that ratio gearbox & powerhead.