Engine Noises on VO

wewantutopia · Post by **wewantutopia** » Fri Feb 23, 2007 10:02 am

I just installed new injectors 3 weeks ago. All sounds fine on diesel. When I switch to VO after about 20 mins. of running, at idle my engine sounds extra "clacky" and it seems to "miss" quite a bit. VO temps are 140*F+. While on VO after idling if I hit the gas and rpms get to ~2000 (no tachomoter) it smooths out. After I switch back to diesel in about 5 mins it sounds fine. Any ideas?

v8volvo · Post by **v8volvo** » Fri Feb 23, 2007 12:03 pm

YES. My Rabbit's engine does PRECISELY the same thing, except maybe a bit worse. After driving with the engine fully warm for over 20 minutes, I switch to VO, and 5-15 minutes later (depending on type of driving -- heavy throttle and high speed makes it happen sooner) it starts getting a little rattly. If I keep going with it, it gets to the point where the engine is clacking horribly at idle and light throttle, and missing and bucking. Under power it seems fine. I notice that in the early stages, if I pull the cold start lever partway out, it makes the noises go away, but it gets to the point where that doesn't help either.

I've run through a bunch of possibilities trying to fix it, including clogged fuel pump banjo connections, air leaks, and plugged filters, and everything has checked out fine. My engine also has new injectors, and has only 10k miles on a known good rebuild. Look for the threads I've started in the past several months in the Biofuels Forum on this site, there's been lots of discussion regarding our problem.

The conclusion I have come to is that the vegetable oil is not getting hot enough, so after a little while of running on VO the injectors and combustion chambers start to coke up. I discovered that when running on VO, even with the engine fully hot for a long time and all the heated fuel hoses and filters hot to the touch, the fuel injection lines still felt cool, definitely nowhere near the 160+ degrees they need to be at for safe VO combustion. You should check yours and see how they feel. I think having relying only on HOH or HIH fuel lines and a coolant-heated filter is just not nearly enough to get oil temps to an acceptable level. The kit you used, and the Greasecar kit I used, are just inadequate I think.

My plan is to add a set of individual electric resistance heaters on the metal fuel lines leading to each injector, to bring the oil temps up above 200 degrees right before injection. I will be installing them when I bring my car out of winter storage in about three weeks. I will report back on whether this solves the problem or not.

My advice is to not continue using your car on SVO while it is doing this, though -- if the problem is what I think it is, then continued use would result in varnishing of the cylinder walls and sticking rings and oil contamination, which could cause major engine problems necessitating a motor tear-down.

Glad to hear someone else is seeing the same thing I am!

wewantutopia · Post by **wewantutopia** » Fri Feb 23, 2007 1:40 pm

The weird thing is before the injector swap there were NO problems; absolutely no difference between diesel and VO. The injectors had well over 100,000 miles on them so I changed them. I'm actually am in the process of putting injector line heaters on. I have two on now, putting the other 2 on this weekend. The reason I only have 2 on is I used 2 to make home made fuel heaters and had to order 2 more. I wrapped 2 3" pieces of brass pipe with barb ends on either side each in a heater . I put one on the line between my pollak valve and the IP. I put the other on the return line between IP and pollak valve. They work GREAT! I've seen an increase of 15*F for only 6 amps used. (I'm using the heaters advocated by Dana Linscott over at the infopop WVO site (http://lineheaterspecialists.netfirms.com/). I'll see what happens after this weekend with the injector line heater difference.

v8volvo · Post by **v8volvo** » Sun Feb 25, 2007 4:30 pm

I tried to find the discussion on the Infopop site comparing the injector line heaters you mentioned to the Fattywagons ones, but didn't see it. Could you post a link? I was going to order my Fattywagons heaters today...what are the reasons why the other kind are supposedly better?

Thanks -- let us know what kind of changes you see after installing these things.

As to why the problems would start after installing the new injectors -- very interesting, hard to say why? Maybe your old injectors were so badly calibrated or worn that they would flow even the thicker, too-cold VO OK, but with fresh nozzle tolerances and breaking pressures the cold VO comes out wrong? I wonder if guys like Greasecar, etc get away with their low level of VO heat because most people never change their injectors, and the difference can't be noticed with worn injectors?

How are you measuring your fuel line heat?

wewantutopia · Post by **wewantutopia** » Sun Feb 25, 2007 8:56 pm

In between the Pollak and IP I put in a brass "T" with barbs on all sides. In the vertical barb I put in a stainless steel food prob that connects to a digital read out I attached to my dash board. Works quite well.

Post by **Fatmobile** » Sun Feb 25, 2007 9:46 pm

Sounds like it needs a timing adjust to me.
Injectors with a different breaking pressure will effect timing.
Not sure what breaking presssure you are using now, compared to before so it might have to be tuned by ear.

v8volvo · Post by **v8volvo** » Mon Feb 26, 2007 11:19 am

That was my first thought when my car started to have problems, except that I've felt retarded timing, and it doesn't feel quite like this. Bad timing causes a more consistent kind of bad running, while the condition I felt was more skippy, less regular -- like it fired OK sometimes, but other times it just wasn't hitting right, and sometimes it felt like not at all. Also, timing problems wouldn't explain the fact that the problems only surface miles after switching to VO.

wewantutopia, any word on the differences/advantages between the two types of fuel line heaters? I can't find much info on the ones you mentioned, though it sounds like either one will do the job. Where can I find Dana Linscott's recommendations that you suggested? I looked on the Infopop forums but had no luck.

wewantutopia · Post by **wewantutopia** » Mon Mar 26, 2007 8:47 am

Ok, my line heaters are on and working, new pollak valve installed so I'm back on veg. again

. Only problem is, even with the new line heaters, I'm still having the same problem

!! So line heaters didn't help it. Time to play with the timing.

v8volvo · Post by **v8volvo** » Mon Mar 26, 2007 10:25 am

Uh oh. I wonder what that will mean for my car...I'll report back once I get mine on, we'll see what effect it has. If it's not this, I'm suspecting problems with the injector pump. I can't think of anything else!

wewantutopia · Post by **wewantutopia** » Tue Mar 27, 2007 9:39 am

Everyday I drive back and forth to school down country roads @ >55 mph for an hour each way. The past few days its been using veg. It runs GREAT as long as the rpms are over ~2000rpms. Once it idles it gets extra "clacky" but it doesn't get worse the longer I drive. It starts after I've been on DRIVING on veg. for ~5-10 mins. Once it gets "clacky," the "clacking" stays at the same level, which isn't all that "bad." It doesn't really vibrate or "miss" or anything; it's just loud. So yesterday after I got home from driving I switched it back to diesel and let the sound go back to normal. Once it sounded normal I switched it back to veg and let it idle for for > 1/2 an hour varing the rpms once and a while listening for changes and the sound never changed!!!! It seems the clacking only begins after the rpms are sustained at higher levels for extended periods of time......how crazy.....

v8volvo · Post by **v8volvo** » Tue Mar 27, 2007 9:57 am

That describes my problem EXACTLY. You're sure there's no air in the lines? My previous theory was that the high revs caused the vane pump to pull harder on the fuel system, sucking in air where it wouldn't have if the revs/power demand stayed low. But I checked and had no air in my lines. My next theory was that if you flowed a lot of fuel through the injectors it turned bad faster because they coked up faster, causing the problems, but the fact that line heaters didn't fix yours blows that out of the water too. What's left? One guy I talked to had the idea that the extra heat of the VO compared to unheated diesel/biodiesel was causing some kind of seal to leak inside the injector pump (piston seal, causing lower injection pressure and effectively retarded timing), or the heat was causing some mechanism to expand and bind up, like the dynamic advance. Problem is, only way to figure out if that's the issue is to tear down and rebuild or replace the pump, which is a lot of $$$...

wewantutopia · Post by **wewantutopia** » Tue Mar 27, 2007 10:16 am

Yep..no air in the lines. All the lines in my engine compartment are clear and not 1 air bubble is entering the IP and all different rpms. I'm gonna mess with the timing this weekend I think.. I've also been reading in the general forum about checking internal pump pressures. I need to fabricate (have fabricated cause I'm not too sure about taps and die etc)something for the banjo bolt to attach a pressure gauge.

Post by **Fatmobile** » Wed Mar 28, 2007 12:39 am

Clacking sounds timing related.
The Fatmobile doesn't do this but I haven't put the timing light on it for anything other than testing the light when I got it.
I think a change in timing will fix it.. forward or back,... I don't know, yet.
It will be interesting to get a pressure gauge in the dash to see how internal pump pressure changes with vegy.

v8volvo · Post by **v8volvo** » Wed Mar 28, 2007 2:45 pm

Yeah, it does seem retarded-timing related, especially since mine actually stops clacking by pulling the CS out (in the early stages of the clacking, before it gets really bad -- after 10 minutes nothing fixes it except switching back to diesel).

But how do you make sense of the fact that it only starts having trouble after being driven on VO for a sustained period of time, esp. at high revs or loads? Also, I know my timing is set pretty far forward already, so I think bumping further in the advanced direction would result in running problems on DIESEL, which I don't want.

Same question about internal pressure...unless it was related to a seal heating up and then leaking, like I mentioned above, why would it wait until 10 miles after switchover to start having trouble? If the internal pressure was always low, seems like it would cause problems right after the VO got to the injectors -- or even, probably, when running on diesel too.

Very strange...I have a good spare pump, maybe when I get home to Seattle in a couple months I'll throw it on and see what happens. Maybe we just have rare pumps that are allergic to VO.

Post by **Fatmobile** » Thu Mar 29, 2007 12:11 pm

why would it wait until 10 miles after switchover to start having trouble? If the internal pressure was always low, seems like it would cause problems right after the VO got to the injectors -- or even, probably, when running on diesel too.

If you have a looped system, the diesel doesn't get flushed away right when you flip the switch.
It mixes with the incoming vegy and becomes vegy/diesel until you drive for awhile... getting richer in vegy as you drive.
V8, do you have a vacuum gauge or fuel temp gauge on your setup?

Former VWDieselParts.com Forum

Engine Noises on VO

Engine Noises on VO

timing

clacking

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