Is fumes in cab definitely failed heat exchangers ?

[MagicWagon]

I have some novice questions for which I cannot find direct answers....
My newly acquired bus smells of engine fumes when you turn the heater on.
Is the only diagnosis failed heat exchangers ?
Is the only remedy replacement of both heat exchangers ?
Am I right in thinking if you get some kind of propex heater then this is only for general heating of the bus, and that this does not help with windscreen demisting etc?
Can you use one of these when driving along ?

[CovKid]

Yes you can use a Propex while going along. I do it all the time in Winter months. Mine is now wired up to a remote control so its toasty before I go to work and it stays on until the normal heating catches up (generally three miles). I recently converted an second hand (£26) LPG tank to supply vapour rather than liquid as I was fed up having to pay more than double for bottled gas, and added an external filler so I can fill up at a garage. Came to just short of a £100 including tank, filler and fittings but excluding heater itself. Works out to £15 a year in gas now and it demists no prob once its up to temperature - melts all the ice too, before I even get out of bed. Before I was paying about £50-£60 a year in gas bottles.

You can also buy purpose designed refillable bottle kits but I wanted something that would fit under back seat out the way rather than sitting in a wardrobe or cupboard. The other option is an underslung tank similar to that fitted to Westfalias although they seem to go for well over £200 even second hand.

First thing I'd do is degunk the heat exchangers so they're spotless and check where any oil may be leaking (ie pushrod tubes and rocker gaskets) as that will make them stink. Its the most common cause of fumes in cab other than rotted exchangers and a badly fitting exhaust. That said, its doesn't compete with the convenience or efficiency of a Propex.

Personally I put good heating way ahead of a gas converted engine in terms of priority. Without it, daily driving in Winter (and overnight camping) can be a miserable affair. Its nice to hear others scraping their cars and knowing I won't have to.

[Jeff J]

I'll second the push rod tube seals causing the smell/fumes

[ghost123uk]

I take it your van is an air-cooled one? (put it in your sig for future convenience )

I will "second" all that CovKid says above I have a very similar setup with a remote keyfob switch to turn it on from inside the house an hour or so before I set off. I use a legally re-fillable 8KG bottle and the saving over normal bottles is huge. Note though that my Propex is a 1,600 Watt one (red case) and it does take at least an hour to get the van warm (and mine is only a Tin-Top camper, so less space to heat up). This does require a certain degree of planning ahead when contemplating "pre warming" for a journey out in the winter, or remembering to turn it on well in advance when overnighting around a camp fire or at a pub etc. The later 2,000 Watt version (blue case) would be better in this respect.

I have read on here about folks plumbing them in to the screen demisters. I reckon that properly functioning heat exchangers (assuming air cooled van) would be a better option though

[petethefeet]

Assuming this is a 2litre air cooled van.
We had similar problems, the cure was to replace the rocker cover gaskets, push rod tube seals and also finally sort a oil leak at the base of the oil pressure switch and then clean the heat exchangers as well as possible.
All a lot cheaper than replacing them.

[MagicWagon]

Yes it's 2.0L Aircooled - updated signature now, thanks.

I'm thinking a propex may be something that I would want to add at some stage anyway, but that looks like it would cost even more than new heat exchangers, so may have to wait. I view that as something of a luxury to keep toasty when camping, but I may have to make do with a cheap oil-fired radiator for that in the short term. I don't think i'm organised enough to fire it up in advance of any journey, and you can't really do that if you're out and have parked it and left it.

Regarding the heat exchangers, it's promising to hear that it mine might not necessarily have had it. However, it does call into question my understanding of the way things work. My simplistic vision of how they work was something like a small tube surrounded by a bigger tube, the small tube carrying hot exhaust gasses, the bigger tube carrying cold air that gets warmed by the smaller tube. I assumed that the fumes were down to failure of the inner exhaust tube, allowing exhaust gasses into the cab.
I'm not sure I understand the alternative scenario of oil leaks somehow causing the fumes. Does the oil somehow get inside the bigger tube onto the hot inside tube ? If so, how do I go about finding out if this is the case ? Where would the oil get in ? Is there some kind of visual inspection I can do to see if this might be the case. If it is the case, how would I be able to clean the exchangers, as I assume the part that would need cleaning would be on the inside.
Also, if it were to be a badly fitted exhaust, where would I be looking and how does this end up in the cab.
I'm a bit reluctant to start taking things apart until I have a clear idea of what i'm looking for, and how big a job I am getting myself into.

[Ralf85]

On an air-cooled the problem may well be heat exchangers. Did you ask the previous owner how long they have been on the van?

[petethefeet]

Hi,
The heat exchangers are a cast finned inner pipe with a thinner sheet metal box around the outside, the air to the cab in pumped by the fan in the engine bay on the alternator in the gap between the inner pipe and the outer box. Oil can leak from the rocker cover and pushrod tubes onto the outer box in through the gaps and onto the inner hot pipe. To clean them I jet washed them and then you have to wait for the oil on the inside to slowly burn off (with your heater vents off)
I am open to other ideas....

[MagicWagon]

The previous owner only had it 9 months having bought it off an old lady and then lost interest while doing up the interior. I do have a pile of history going back to about 89. Not sure if it's complete but I'll have a look through and see if the exchangers have ever been replaced.
Meanwhile, it definitely has a minor oil leak - not enough to leave anything much on the ground, but enough to coat the underside of the engine. The PO said he just had the rocker gaskets changed, so I need to have a close look underneath and see if I can see where the oil comes from and goes.
Is it safe to assume if I find oil on the outside of the exchangers then it is probably inside as well ?

I looked at the wiki regarding changing the seals. The procedure sounds doable until the last line where it starts going on about getting TDC etc, where I start to panic slightly.
I looked at this guy doing it on youtube - awful video - He says not to worry about TDC. However, his tubes look to be in two parts, whereas those on justkampers look to be one peice, so not even sure it's the same engine. Is he talking nonsense ?
If I decide this needs doing, should I replace the tubes as well as the seals, or should they be OK do you think.
Thanks to all.

[sarran1955]

Hello,

Aircooled bliss...

The steel tubes that conduct the exhaust gases will outlive both of us..

Air cooled engines run best when clean.....I mean really clean.

The heat exchangers are just tinware and loads of fibre crap wrapping round the exhaust tubes (which have dinky ally castings attached}

Theses fill up with oil and gunge.. hence 'that classic Aircooled smell'

Take a torch and have a GOOD look.. if the tinware is reasonably intact.. yes you will have to remove the bottom cover plates..

I wonder if there is one missing..

then after a good clean and a bit of exhaust bondo..

then you look at the linkages and hoses..

Many armchair experts will tell you that the heating is no good in these vans.. this is because they have not removed the petrol tank and replaced the collapsed foam and paper tube that runs the whole length of the van .. from the broken plastic bits at the back.. past the crushed bit over the fuel tank..(also stinks because of perished rubber tubes) to the fallen off paper tubes at the front

Then there are the wongy cables and all the missing bits...

Plus you can't see the controls in the dark

Aircooled bliss.....

Cordialement,

[MagicWagon]

It took look underneath and there is bit of oil coming from 2, maybe 3 push rod tubes, but not all. There is oil on the heat exchangers, but not a huge amount. I assume the place it can get inside is around where the exhausts go into it, but I can only see on one of those where it is oily. It looks fairly claggy and gunged, so it's not like oil could run inside the heat exchanger easily.
If I am to tackle it, can anyone tell me if the final step of this wiki instruction is actually required ?
https://club8090.co.uk/wiki/Pe ... eplacement" onclick="window.open(this.href);return false;
I.e the TDC/adjusting rocker screws bit, as I watched someone on youtube doing it and he made no mention of this. That part puts me off attempting it as I would not be confident about how to do this. Haynes manual seems to be no help at all with this procedure.
https://www.youtube.com/watch?v=V3VOcuqTcTQ" onclick="window.open(this.href);return false;

[CovKid]

As I said earlier, completely degunk exchangers. Once they're clean, dry and any remaining degreasant burnt off, you can evaluate things again. In good fettle, Aircooled exchangers work very well (I once melted some wellies so can vouch for that) but even a moderate oil leak can get worse once the engine is hot and you won't really see anything until they're spotlessly clean. Trust me, when things are hot and you're flying along, oil can and does work its way in - through even the tiniest gap.

[MagicWagon]

When you say degunk the exchangers, do you mean the outside of them with them in situ, or do you mean take them off and somehow clean inside ?
Thanks.