Diesel engine valve position during layup

[Guest]

At the beginning of the season I had lots of trouble starting my Volvo 2001 diesel.

A local engineer suggested that during the winter rust must have accumulated on the valves ? (and tappets). I had no further trouble during the season.

He got it going by squirting WD40 in the air cleaner whilst turning the engine over..

If I remember correctly, he suggested that the engine should be left with the push rods ? making contact with the tappets.

I would be grateful for any advice on this and how I could leave the engine in the correct stroke during layup. I can turn the engine OK with the alternator belt.


Many Thanks

 

[andy_wilson]

Since time (or at least diesel engines) began, a single cylinder diesel will stop at the start of the compression stroke. with everything closed.

I think that's probably the best way to be.

At the top of the exhaust stroke both valve trains will be activated (exhaust almost closed, inlet just opening) giving cold damp air access to the upper cylinder for the entire winter.

 

[stubate]

doh !! engineer ?
since time began, diesel engines stop where they want to, ie on the next stroke in the cycle where a piston comes up against compression.
the reason that the engine wouldnt start easily after the layup is because possibly there is wear in the piston rings and or bore and the residual oil has drained away giving a less than optimal seal and so lowering the compression.
wd40 has a flammable propellant that is easily ignited by the compression of a diesel engine, that is why you can use it in extreme cases as an aid to starting, it works in much the same way as easy start, tho not as extreme, if the "engineer" just used it whilst turning the engine over, it will have lubricated the bore and increased compression, if he used it to start the engine, it will have worked because of the above explanation. either way it worked but the idea of turning a diesel engine to a position to leave it !!!!
s

 

[colinroybarrett]

On a multi-cylinder engine there will always be at least one valve open. The wet exhaust system is likely to have some residual water in the lowest point and there is bound to be a cold, wet gale blowing up the pipe several times over the winter period, all of which will allow some rusting of valve stems, seats or cylinder bores.

It’s none too onerous a task, whilst ‘Winterising’ the engine, to whip off the inlet air filter and cover the inlet manifold orifice with a ring cut out of a thick plastic bag, hold it on with masking tape. Do the same with the exhaust pipe and manifold outlet.

Usually, just before ‘finally’ stopping the engine, I’ll dribble a little engine-oil into the inlet manifold to load up the surfaces with as much oil as they will take, then bag it up, as above, should stay nice-n-dry and rust-free over the winter.


Cheers,
Colin Barrett
<A target="_blank" HREF=http://www.kahawi.co.uk>http://www.kahawi.co.uk</A>

 

[david_bagshaw]

Another way, not quite so good


loosen the rocker shaft bolts so all valves are closed.

David
<A target="_blank" HREF=http://www.euroboating.net>http://www.euroboating.net</A>

 

[johnt]

Im with stubate on this one ROFL ....that engineer was just winding you up !..and justifying his charges !

 

[Guest]

Probably right John !

Perhaps this was a case of 'engineer's licence' or he was too nice to tell me that the thing was knackered.

Might be something in it though because I even tried 'Easy Start' which didn't work.

These one lung Volvo's seem to have a bad history for starting even when you give them extra splash of diesel with the lever. Volvo's do a glow plug kit for em which does not inspire confidence in the product.

I am still in the water and she still started ok in this cold snap.

 

[Strathglass]

Re: He may be correct

I have a single cylinder Honda petrol generator, about 1Kw. The instructions state that . When leaving the engine unused for any length of time the engine should be set at the position where the valves are closed.
There are two reasons for this, 1 - the valve seats are closed and tend not to rust. 2 - the valve stems between the valve guide and the valve head only rust near the head.
If the valves are left open then rust on the stem can jam the valve in the open position and the valve spring does not exert enough pressure to open the valve.

I learned about this when I purchased the generator. It looked immaculate but had been stored, unused for some time and would not start. The cure was quick, easy and cheep (Honda not Volvo) .
I removed the head, pushed the offending valve back down, lubricated the valve stems then reassembled it using the original gaskets. That was eight years ago and it still runs fine.

Perhaps there is something in Old Wifes Tales

Iain

 

[Strathglass]

Re:slight correction

The rust on the stem holds the valve open not closed as I said.
Iain

 

[seaesta]

My single cylinder volvo allways stops with the valves open and whenever I leave her I wind the engine round onto compression to ensure the valves are closed. Doh ? Plain commonsense I think!

For winter layup a couple of squirts of Magnatec into the cylinder and 1 rotation of the engine to spread the oil round the piston belt also makes sense

 

[Johnjo]

Not so easy with twin cylinder

 

[toad]

Re: He may be correct

On a old generator turn it up to compesion then back it off 10 deg or so,not only will the valves be closed but so will the contacts.It will help stop the faces rusting.

 

[Mirelle]

Happened to my Volvo once

after a long lay up. I have now given up laying it up and run it once a week or so!

 

[lauradee]

at the start of the compression stroke both valves are closed, thats how you get compression

 

[lauradee]

when you leave your diesel car at the airport for a months holiday do you open the bonnet and turn the engine over to what you percieve to be an optimimum position?
i dont think so !!

 

[lauradee]

thanks
s

 

[lauradee]

if easy start didnt start it it was the lube quality that did the trick, by the way the reason that easy start knackers the engine is that the ether explodes instead of burning ina controlled fashion at too far an advanced position in the timing cycle and breaks the piston rings, thatrsa why you get the urban myth that engines get addicted to it,
sb

 

[seaesta]

I would do if the car engine were a 1965 single cylinder job and I was leaving it regularly in a marine environment and for weeks at a time.

Comparisons between the above and a modern multi-cylinder turbo diesel car engine are facile.

 

[stubate]

facile as in easy ?

 

[seaesta]

oops! facile as in pointless