Ticking/knocking/nailing on WVO

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vibraphone321
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Posts: 28
Joined: Mon Oct 15, 2012 8:12 pm
Location: tucson, az

Ticking/knocking/nailing on WVO

Post by vibraphone321 »

The rabbit is running great on diesel, smooth, quiet, no noises. But when I switch to WVO (two tank heated system, switching at 165f) I get some clattering. Its noticeable at idle, pretty bad at low speeds under a load (taking off in 1st and 2nd gear), and then goes away completely in higher gears. When I switch back to diesel the sound goes away completely as well (in all gears). I put about 1/2 oz of Sea Foam in the WVO filter to see if it would clear things out and it did or about 10 miles, but now the sound is back - although not as bad as before the Sea Foam. It has been in the 30f's here lately, but like I said, I have been letting it warm up - and the WVO gauge is showing temps between 120-150f.

Is this anything to worry about?

I have read that WVO effectively retards timing because of the way it burns and that people are advancing timing to make up for it. Would something like this explain the noise? I like the timing where it is for everything else - good mileage/power, smoothness, cold starting.

What about pulling the cold start on WVO to advance the timing a bit? I read something about that, but haven't tested it yet.

Thanks in advance.
'81 Rabbit, 2 tank WVO, 1.6 NA, 4 sp Manual, 245000 miles
Fatmobile
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Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

Re: Ticking/knocking/nailing on WVO

Post by Fatmobile »

Mine is more clacky on wegy also.

I figured it is either fuel that explodes quicker (higher cetane) or it is causing the injectors to spray differently.
Because it quits at higher RPMs leans more toward timing.

That pinging can be a good indicator of where the injection is in relation to TDC.
If we could make it so the noise would continue throughout the range the curve would be correct.
We could just back the static timing off a little to reduce the noise and be happy at all RPMs.

But then diesel might run like hell, all retarded with white smoke or low power.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
vibraphone321
Cetane Booster
Posts: 28
Joined: Mon Oct 15, 2012 8:12 pm
Location: tucson, az

Re: Ticking/knocking/nailing on WVO

Post by vibraphone321 »

Thanks Fatmobile. Is your happy medium leaving it how it is? Running well on diesel and a little noise on WVO in low gears?
'81 Rabbit, 2 tank WVO, 1.6 NA, 4 sp Manual, 245000 miles
Fatmobile
Global Moderator
Posts: 7564
Joined: Wed Oct 30, 2002 10:28 pm
Location: north central Iowa

Re: Ticking/knocking/nailing on WVO

Post by Fatmobile »

Yeah, I usually run as advanced as I can.
So how it runs/sounds on vegy is kinda what limits the setting.
'91 Golf gasser converted to a 12mm pump, M-TDI.
'84 1.6TD Rabbit with a VNT-15 turbo, still setup to run on vegetable oil.
'84 GTI with 1.7TD pistons and intercooled.
2003 TDI wagon
2000 TDI Jetta.
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