A salutary tale for the Aircooled amongst us

Post by **cumbriankeith** » 17 Jan 2008, 20:05

I've been clearing out my garage/workshop and am about to chuck some stuff away, including a couple of cylinder heads. I thought people might be interested to see the possible results of overheating...

The first couple of pics are of the head that I replaced just after I bought the camper nearly 8 years ago - I got it very cheaply cos the engine sounded like a machine gun ( I did not drive it home!). When I got it apart the reasons were obvious:
[IMG:500:375]http://i90.photobucket.com/albums/k260/ ... kenup2.jpg[/img]

[IMG:500:362]http://i90.photobucket.com/albums/k260/ ... kenup3.jpg[/img]
I'm not wishing to patronise anyone but for those with less experience we are seeing the bits from the broken up valve seat having been pounded into the cylinder head, looking like nuts on an iced cake. It's the inlet valve that has failed to stay where it should and we can see a (dark) ring round the (smaller) valve head, which is the space where the seat used to be. This is what it should look like - with a little coke build up and so on but otherwise in good shape:
[IMG:500:347]http://i90.photobucket.com/albums/k260/ ... Normal.jpg[/img]

More recently, last summer in fact, I had the misfortune to suffer something similar - bad noises, tho not quite as bad as before, and loss of power. I got someone else to do the work for me this time (thanks again Colin in Barrow!) and what was found looked like this:
[IMG:500:341]http://i90.photobucket.com/albums/k260/ ... enseat.jpg[/img][IMG:500:375]http://i90.photobucket.com/albums/k260/ ... shapen.jpg[/img]
This time the seat had not broken up - it had wrecked the head but at least the piston was still ok - it only suffered a very slight mark that was smoothed out.
Here's some more pics from different angles, with and without the valve in place - the dislodged seat had been pounded into the head by the piston hammering on the valve but in two different positions - with big indentations to show this. Even the valve seat, which is made from really tough steel has been marked by this pounding.
[IMG:500:375]http://i90.photobucket.com/albums/k260/ ... tright.jpg[/img][IMG:500:375]http://i90.photobucket.com/albums/k260/ ... utleft.jpg[/img]
[IMG:500:375]http://i90.photobucket.com/albums/k260/ ... tright.jpg[/img][IMG:500:375]http://i90.photobucket.com/albums/k260/ ... utleft.jpg[/img]
[IMG:500:406]http://i90.photobucket.com/albums/k260/ ... nseat2.jpg[/img]

And the moral of this tale? Keep your engine in tune, don't let it run on a weak mixture and don't let it run too hot.
How hot is too hot I hear you ask? - well that's another story....
[Gauges are available to help with this!]

Anyone with more engine wisdom to impart than me - feel free!

Post by **Rozzo** » 17 Jan 2008, 20:37

driven carefully this should be avoidable but this is excellent information m8

i've slackened the throttle cable on mine so it will only do 65 flat out but it just burbles along and never really gets that hot.
look after em everyone cos decent engines are getting expensive. one just finished on fleabay making 550 quid

Post by **Dan Wood** » 17 Jan 2008, 21:07

Woooooaaaaah! What have I just bought?

Should I get my 1.9DG lump back?

Post by **Rozzo** » 17 Jan 2008, 21:31

you'll love it dan

Post by **toomanytoys** » 18 Jan 2008, 08:56

Ignition timing is crucial on these engines.. My feeling is the std setting is too retarded and a slight advance should be made, especially as they run on 95UL as IIRC they are set up to run 92UL...... (2 star)

95UL is more resistant to "knock/Pinking" and the combustion takes place slightly later because of it, this puts heat up the exhaust..

This is one of the factors with LPG.. why everyone says to advance the timing... same thing happens..

Post by **Tex Ritter** » 18 Jan 2008, 11:17

Jings Keith!
If I had seen those pics before I drove up Mount Ventox in South of France in 31c degree heat I would have been extremely worried.

Tex Ritter

Post by **cumbriankeith** » 18 Jan 2008, 11:29

Glad to hear it's of interest, Rozzo.

I suppose the other things that need to be in good order and not jammed closed in the wrong place is the cooling-air flaps - the thermostat should failsafe so the engine would be overcooled, or more accurately, slow to warm up in cold conditions. If the flaps have been left out altogether then this is very bad - one of them is really important in that it directs air into the oil cooler. When Laurie Pettitt built me an engine he suggested an extra oil cooler, possibly in the airflow pulled in by the alternator-mounted fan, would help for loaded campers. Anyone done this??

I think I'm guilty of sometimes expecting too much of these engines - I drive modern turbo diesels at work and have a Golf GT Tdi 130 as a daily. Then I go and forget that a 25 year old loaded camper, sometimes with a big open canoe on the roof will not do anywhere near the same performance on the motorway or up hills etc with an engine of half the power. I need to be even more reasonable and kind to it! - which I am most of the time... I was in Spain last summer and it was fairly hot - oil temp was reading around 130 a couple of times, but I'm not entirely convinced the gauge is accurate.

If anyone thinks this is worth putting in the wiki then carry on - I've not got round to figuring out how to do it.

I'm assuming that these heads are scrap - beyond economic repair?? Or should I hang on to the better one in case things get silly in a few years time?

Post by **Tex Ritter** » 18 Jan 2008, 12:03

[quote="cumbriankeith"
I think I'm guilty of sometimes expecting too much of these engines [/quote]

I fall into the same category Keith, we're always fully loaded on our jollies but sometimes forget that the engine is of 1980 vintage.

Tex Ritter

Post by **DaisyAirHead** » 18 Jan 2008, 12:45

I totally agree with all these postings.

I am afraid, somewhat "old fashioned"in my approach to engines!

I always let the old girl "warm-up" first before setting off

Air cooled lumps are great if set up properly.I "cut my motoring teeth" on air cooled bike engines.24 hr endurance racing with air cooled ducatis.Still got Moto Guzzi air cooled cafe racer and if you think VW engines are crude!!!

Change oil and filters at twice recommended intervals.

Try to avoid sitting in traffic in summer and always try to get an air flow to the motor preferably by keeping moving.

Remember you are asking a lot from an engine that is no more than a glorified beetle lump and expecting it to perform the same as a modern motor will cause major probs long term.

I take the old girl away frequently with a family of four,two large dogs,driveaway awning,boards and wetsuits and enough family "crap" for two weeks.Think how hard the motor works at 60mph fully laden trying to play tag with the juggernauts on the motorway!!!

You will get there in the end just more slowly!!

Top end rebuild shortly for the girl but at 110000 miles on original heads,valves rings etc ain`t bad in my book!

Also don`t get paranoid.Despite all their foibles These engines are great!!!

Post by **jason k** » 18 Jan 2008, 17:02

once set right these motors are super tough, the faster you go the more air gets pumped , its not revs that kill em its labouring in top when you should be down a gear!!
mixture and timing are crucial, i found (on a rolling road) my stock solex carbs were running far too lean at the top end, so had the jets opened which was much better in terms of performance and mpg, later i had a pair of delortos on, but again i took it to be jetted properly on a rolling road. when you buy carbs they will come with jets from the suppliers but EVERY engine is different and thats why you should always get them set on a rolloing road.
my old Aircooled would sit at 70 to 75 mph no problems and steam up hills! and that was a hi top too.
set them right and they are a fantastic motor.

Post by **fergus77** » 19 Jan 2008, 08:48

just to add,

i had the same problem. Bought a van which was diagnosed as having a completely knackard engine.

Pulled the head off and found something very similar. It was a 1.9 1Y diesel engine which compltely melted the head between the valves

for some reason i can't put the picks on the post but looked the same as the above head. Again, slight marking to number 4 piston and a hell of alot of crap covering them. Every cleaned up just fine though and the reconditioned head is being fitted today

Post by **cumbriankeith** » 19 Jan 2008, 11:45

I've figured out how to Wiki it and have now done so.

Jason, what rolling road did you take it to and how long did it take/how much cost??

Post by **jason k** » 19 Jan 2008, 15:30

race shack in tewkesbury.
www.raceshack.co.uk
it cost about 180 notes for the setting up and loads of runs on the dyno to tweak fuelling and timimg. cheap if it saves a melt down eh??!!!
left there the second time (first was to re jet my solexs) after fitting my dells, with fifteen more horses at the wheels!!
huge difference and good lads who fully understand the Aircooled motor.

Post by **germman** » 20 Jan 2008, 01:08

jason k wrote:once set right these motors are super tough, the faster you go the more air gets pumped , its not revs that kill em its labouring in top when you should be down a gear!!
mixture and timing are crucial, i found (on a rolling road) my stock solex carbs were running far too lean at the top end, so had the jets opened which was much better in terms of performance and mpg, later i had a pair of delortos on, but again i took it to be jetted properly on a rolling road. when you buy carbs they will come with jets from the suppliers but EVERY engine is different and thats why you should always get them set on a rolloing road.
my old Aircooled would sit at 70 to 75 mph no problems and steam up hills! and that was a hi top too.
set them right and they are a fantastic motor.

whs ...Fantastic ! ! .... and jase and i are both big fan's of the AC lump , If you own an AC motor you need to rev it they have a rev limiter on them so you canot over rev them rev's = cooling air for both oil and head's , an absolute mist is a rolling road sesion ,i have used race shack but TVR power in coventry have a brand new rolling road and they also know loads about ac engines al be it bike stuff !
i have raced my ac engine hard for the last 2 seasons and apart from oil and filters and a quick pre season tune up haven't needed to do anything to it ! i tow a small caravan to santa pod with it up the incline on the m45 with no problems ! ...Ok i have spent a few bob on the engine but its still an ac 2Ol and just to give you an idea of what there capable i backed off at 6300 rpm @about 110-115 mph thats a guess since the speedo only goes up to 100 ! !

Post by **Dan Wood** » 20 Jan 2008, 13:02

I just got one, this weekend and I'm not sure if I've got the idea right...

It'll maintain 40mph or so up a steep incline in 4th, and it'll rev its bits off on the same hill at about the same speed in 3rd...

So 3rd... is the way to go? Rev the thing?

Also, do they all leak oil? Stopped off at my mum's on the way to the ferry and she wasn't happy about the state of her driveway afterwards!