WVO: solvents for cleaning up the fuel system and engine?

[mosheshimon]

Thanks, guys, again.

I will have a rummage under the back seat sometime and try the tank filter.

The conversion was done by an earlier owner (I'm the 7th). He/she fitted a modified plastic "spare gallon" can behind the under-the-bonnet panel, next to the windscreen wiper motor. This holds about 5 litres of normal diesel for cold starting, which passes through a small disposable inline fuel filter on its way to the Polack valve. That leaves the boot space unencumbered. The veggie oil is in the main fuel tank under the car and passes through a heat-exchanger (warmed by engine coolant) before going through the car's original filter and then on to the Polack valve.

Because the vast majority of my journeys are extremely short I found that in reality I was driving 95% on the small diesel tank before the engine had heated up enough to allow me to switch over! Almost no £-savings whatsoever! So one of the Club members suggested thinning the veg with a bit of petrol to remove the strain on the IP and then using the thinned veg right from cold. This seemed to work fine for well over 1000 miles, until the present problems arose.

I must confess that I'd hoped the 10% petrol would dissolve away any existing deposited veg gunge and prevent any further deposits by keeping it all in solution. Clearly that didn't work or else a completely different issue has arisen. It's the facts that all works fine when hot and also that it misbehaves when cold even on the pure diesel that confuse me. After all, the cold-start diesel runs through a completely separate filter and stays cold until reaching the injectors! Very puzzling. Maybe it's a build-up from all the many times a tiny bit of WVO has gone to the diesel supply via the return pipe immediately upon switching back to diesel at the end of a journey? It doesn't seem terribly likely to me, but one never knows for sure.

I think when I get to the main tank filter I shall change/clean all 3 fuel filters and also increase the blend of petrol to about 15%. Or else top up with 5-10% Isopropanol just for a limited time. Or both.

Thanks again for all the help and advice.

[MULLEY]

Any further news on this?

[mosheshimon]

Ambiguous results! After a few days internal soaking in around 20-30% or so Isopropyl Alcohol (IPA) the improvement was enormous. Instant starting again! No cold stalling! Much smoother running (but still a bit jerky). All without having got round to changing or cleaning a single filter. BUT my son just back from college says it is significantly under-powered; as a gradual change I hadn't noticed it creeping up on me, but HE last drove it many months ago and noticed the difference immediately.

However, the jerkiness hasn't gone away yet and is possibly getting a bit worse again, but mainly when we're switched to the main (oily) tank. On the auxiliary (cold-starting) tank it runs much more smoothly (though not 100% perfectly), but that could be for a variety of reasons... it's real diesel and IPA blend with no oil in it / maybe IPA-loosened gunge from the main tank has now clogged the main filter / maybe the main filter is disintegrating because of the IPA (shouldn't happen, but one never knows!) / maybe loosened gunge formed a fine suspension in the main tank system which is getting through the filter and causing brief partial blockages / maybe a hundred things I haven't thought of yet.

Whatever the actual cause, my next step has to be checking and/or replacing the filters in order of accessibility!

More news when it happens!

[jonathan_dyane]

With such a massive amount of IPA added, I'm not surprised that you're down on power; it will have massively reduced the cetane value of your fuel...

[mosheshimon]

Hey Jonathan

Thanks for that, it's really boosted my hopes; maybe when I refill on straight diesel the remaining problems will disappear as the IPA concentration plummets?

As a World-Class Olympian ignoramus and twit I kind of thought that IPA would actually boost power - isn't it the stuff they fuel racing cars with?

I have never found out what cetane actually means. Lots of alchemy products of the snake-oil variety seem to cite it knowingly and/or wisely as a desirable feature/property/ingredient of their potions, but they never take the plunge and clearly state what it really is! I never got further than discovering that a cetane level is a very different beast from a cetane number, and one of them is in effect virtually meaningless. Can't remember which one. So I sort of shelved the concept as a mechanical equivalent to hair-restorer lotion. Perhaps I should treat the car to one of their magical elixirs?

Anyway, thanks for the encouraging advice.

Regards and thanks

MS
PS: do you happen to know anyone with a spare BX Estate tow-bar?

[jonathan_dyane]

Not many racing cars have diesel engines! Hopefully like you say, normal service will be resumed running in straight diesel.