help my valves are sinking.

After lots of fault finding and carb setting electrical fault tracing etc... it looks like my misfire on no3 is down to sinking valves. looking through the valve setting history the exhaust valve on number 3 keeps getting tight. this is cusing the misfire at tick over and the lower compression.

so. what happens now? I know i will need a new head but why is number 3 getting so much hotter to cause this?

which head should i buy. There is so much crap out there i want to try to avoid this in the future.

any estimate of how much ot might cost to get the head replaced in terms of garage costs?

cheers all.

 

This is a type 4?
The overheating problem is often caused by servo air leak leting it run hot. The problem may aleady be dealt with, but once the seat is a bit loose it'll keep bashing its way into the head.

 

1641 type 1 I do believe!!

what carb do you have on it? is it a solex or a brosol?

 

Scratch that... you have ICTs..

could just be a bad head... hard to say without looking at it!!

 

Booking the van in for the engine to come out. thanks everyone for the help getting this sorted so far. I have been through all the cheaper options hoping that it wouldnt be this but hey ho.

 

Stick some pics up of the head once you've got it off!!

 

Its probably being running lean on one side

 

How do you tell if it is running lean on one side when the sniffer goes into the exhaust tail? mixture screws are set the same. The carbs are clean now as i have just had them apart and cleaned them out. didnt find much but did change the emulsion tubes from F78's to F6's.

 

This is where the old way of the gunsons colour tune pays the investment especially on a twin carb aircooled

You get to actually see the colour of the burn on each cylinder

 

oh yes, forgot about those. what do you look for in terms of colour? I have an amazon voucher. will get one. Anyone used them on a type one engine? how easy are they to get into 1 and 3 cylinders?

 

how involved is replacing a cylinder head?

 

Engine out... tin off... basically all the way down to a long block... gonna take you an hour or 2 to get it stripped down

 

will the barrels separate when i remove the heads. if so is this an issue. can you just bolt them back up?

 

don't sweat it.. just bolt them back up... Although I have had them where the barrels are jammed in the heads, and you have to pull a head and pair of barrels in a one-er!!

 

... but while you're at it, why not reseal the barrels to the block. I bet they show signs of leaking especially if it's been overheated. A simple piston ring compressor is a few quid off JK and that's all you need.

...and while you've got the barrels off, why not take the pistons off and the con-rods and replace the big end shells - just a few more hours and about a tenner for the shells - no block splitting required.

...oh bugger it - strip it down and replace all the bearings.

 

Its not your valves sinking at all, I would imagine................much more likely that they are stretching.
If its the No. 3 exhaust valve (as it was on my bus) you might be able to get away with just replacing the valves, hopefully the heads are still "S".
GET AND HAVE A LOOK RIGHT AWAY, a dropped valve is not funny.
Tony