WVO system slowly losing ability to heat

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WVO system slowly losing ability to heat

Postby Guisepi » Sat Mar 12, 2016 4:02 pm

Howdy all,

I have an '89 Ford Econoline (short bus) with a 7.3 IDI motor. Clean system is as follows: Custom heated fuel pickup > 10 plate FPHE (to bump up temps for pump) > fuel pump (Airtex E8153) > Coolant coil wrapped filter with coolant heated head (WVO Designs) > HIH (3 feet about) > 30 plate FPHE > 3 way switch > Vegtherm (for optional heat) > IP.

This system worked great for the past 3 years, but all of a sudden, it seems to have a much harder time heating the oil. Whereas I was cruising fine in cold weather at 160F before, now I need to run my VegTherm (which bumps temps about 15F), and even then it sometimes isn't quite hot enough. Even now in 70F weather, it's not even keeping 160F at idle.

I thought it was the way I had mounted my FPHEs (both face down - I know, it's a no-no, but I had few options space-wise). I took the main FPHE out and inspected, half expecting to find a bunch of poly. When I took it out, it seemed pretty clean inside. I gave it a good clean (hot water, soaked with Dr. Bronners, more hot water, and fan dry). Not much came out. I put the system back together, this time with the FPHE on its side, with the WVO ports on the upper half so that no air could get stuck in it.

But, alas, still having problems with temp.

Does anyone have any ideas as to what the problem might be for diminishing WVO temps? Could there be poly build-up inside the FPHE that I just can't see?

I think the coolant is circulating fine (I have a coolant heated hot water heater at the end of the coolant loop, and it gets plenty hot).
Guisepi
 
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Re: WVO system slowly losing ability to heat

Postby SunWizard » Sat Mar 12, 2016 6:12 pm

Do you have an accurate coolant temp guage to see if the thermostat is bad? My truck had a bad one when I bought it, and the cummins ran way too cool. And the stock guage doesnt have accurate numbers to tell much.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
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Re: WVO system slowly losing ability to heat

Postby Guisepi » Sat Mar 12, 2016 8:06 pm

Yes, temp gauge is aftermarket and accurately reads my coolant temp at 192F, which is what the thermostat is at. :-/
Guisepi
 
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Re: WVO system slowly losing ability to heat

Postby SunWizard » Mon Mar 14, 2016 1:03 pm

Sounds like an air bubble or restriction in the coolant line someplace. You could try disconnect the coolant line near the end where it returns to the engine, and run the engine and see if you get a steady stream of coolant out of the hose, and into a bucket to save the coolant. This also would help purge any air in the loop. Check the lines to ensure there isnt a place that has trapped air, which I have gotten after a coolant leak.
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
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Re: WVO system slowly losing ability to heat

Postby Guisepi » Wed Mar 16, 2016 11:42 am

So, I checked the coolant flow after the clean WVO loop, and there's plenty of flow (anyone else doing this test: make sure your radiator cap is off to allow air in to replace the coolant coming out, otherwise you may have an incorrect reading, as I did initially).

My system is a little more complex than I led on to before. After the clean WVO system, there is a manifold of three 3-way valves that allow me to control where my coolant flows. It can go back to the engine, to my coolant-heated hot water heater, or my dirty WVO tank (for heating/settling, centrifuging, and filtering). My clean WVO temps are the same no matter if I shut the extra components out of the system (sending the coolant right back to the engine) or not. Nor does it make a difference if I turn on my extra 12v coolant pump (from an 80s Mercedes diesel) for extra flow.

I have been planning a replumb of my coolant system for a while to make two shorter loops (one from each engine head), where one loop is for clean WVO and the other is for dirty WVO/hot water heater (and heater core, which is currently on its own small coolant loop). I am thinking of doing the replumb now, which will allow me to inspect some of the valves internally, as well as some other components.

Questions:

If it isn't coolant flow that's the problem, what else could it be?
Even though the FPHE seemed pretty clean, could it have poly in some of the passages?
Perhaps my temperature probe is incorrect? I'll try cleaning the electrical connections and see if that changes anything. Actually, I have a spare probe I may just swap in.

Any other ideas?

Thanks!
Guisepi
 
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Re: WVO system slowly losing ability to heat

Postby SunWizard » Wed Mar 16, 2016 4:39 pm

Guisepi wrote:If it isn't coolant flow that's the problem, what else could it be?

You guessed the 2 I was thinking of.
Even though the FPHE seemed pretty clean, could it have poly in some of the passages?

Yes, and if there it would also show other places. A thin layer could be hard to see since it can be transparent and you may have to scrape to notice.
Perhaps my temperature probe is incorrect? I'll try cleaning the electrical connections and see if that changes anything. Actually, I have a spare probe I may just swap in.

Good idea, maybe try it in a bucket with a known temp of heated water to compare. (like heat some water to boiling which always occurs at the same temp. at your elevation, or use another way to know the real temp.)
YVORMV - Your veg. oil results may vary.
95 Dodge Cummins 4x4 SVO WVO conversion.
81 Mercedes 300D- stock and happy on V80/D20 blend.
Low fossil net zero house- 100% solar power and heat.
SunWizard
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Re: WVO system slowly losing ability to heat

Postby dragonfly » Thu Mar 17, 2016 1:05 am

Have you checked the coolant thermostat for proper operation? IMHO, running WVO @ 160F is not very hot. AC Delco PN 12TE1E, 195F @ $3.95 was listed for the Econoline. VO likes as much heat as possible. To take the possible air out of the coolant system, remove the radiator cap, make up an extension and attach it to the return coolant hose long enough to reach the top of the radiator filler neck. Start the engine. Check the flow since the thermostat will open up and allows the coolant to flow.
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Re: WVO system slowly losing ability to heat

Postby Guisepi » Thu Mar 17, 2016 8:03 pm

dragonfly, I guess I wasn't that clear before. The 160F I was talking about was WVO temp, not coolant. As noted previously, my thermostat seems to be working fine as my aftermarket coolant temp sensor reads the appropriate 192F for the OEM thermostat. Thanks though!
Guisepi
 
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