I'm in the process of modifying my '85 740 TD to run on Waste Vegetable Oil. In the process I need to run tap into a coolant feed and return line to be used a heat exchage source. I'm not quite sure where to do this.

This is a link to page with a picture of my engine.

http://mypage.iu.edu/~kjcase/TheCaseFamily/vegeng.htm

Highlighted in green is the hose leading to the cold start device, I think. In blue I'm not quite sure if it's a feed or return line. Could someone please help me in recommending the best way of tapping into the coolant system for my project.

Thanks

jerry

Nice photoshop job, that is realy clear.
What conversion parts are you using?

Oddly, due to VW's backwards $40 thermostat design;
Green is return from the cold start device.
Blue is return from the oil cooler.

The best way is to eliminate the POS VW oil-coolant heat exchanger and use the hoses for your SVO heater. I did this by using an air-oil cooler&hoses from a Saab turbo, and thermosttic oil filter/cooler adapter form a Gas turbo 740. saab oil cooler lines worked fine, but they are often old and leaky, so you might want new ones.

Generaly the closer to the firewall you can tap in, the cleaner the conversion will look.

If you do want to use the VW oil cooler(VW recomend a $360 replacement unit every time you work on the motor, but I can find them as low as $85..they DO fail in a number of evil ways), you can get a free return fitting by usin a resevoir to radiator return hose from a later Gas Turbo car with the water cooled turbo...Looks very clean and maintains OEM quality.

The oil cooler feed line at the back of the motor is a good place to grab hot water, but is a wee bit hard to reach.

I can send anyone some pics of my setup on request, but I have made a radical departure from how VW designed the 'system'

AVOID PLASTIC COOLANT FITTINGS LIKE A PLAGUE!!! I like to get molded hoses with a 'T' at the junkyard, or use brass fittings.

Rowan,

Could I tap into the hose that feeds into the cold start device as my feed line and then tap into the oil cooler hose for my return for my heat exchange system? Would this be enough to create my loop?

I would love to just tap into the heater hoses but there isn't enough room for me to get to the hoses and they seem to have already "T'd" into other hoses.

Thanks

Jerry

Yes, the blue hose will be your return. the cold start an heater input hose are actualy shared. The routing under the injection pump is not the hot setup, but Volvo seems to have been OK with it.

Ill try to get some pictures of mine if the sun comes out today.

posted details of my oil cooler upgrade:
http://www.brickboard.com/RWD/index.htm?id=952355&nr_no=1

Rowan,

I forgot to ask about seeing photo's of your conversion.

Thanks

jerry

Rowan,

I'm using conversion instructions from a gentleman by the name of Dana Linscott. He has plans that show you how to construct simple heat exchangers using simple copper pipes fromt he hardware store. He has been a great help in this whole matter. Here is a link to his website.

http://vegoilconversions.netfirms.com/

Thanks for you help! This will help me in finishing up my conversion this week. When I'm done I post a link to my site detailing my conversion work.

Thanks

jerry

When you complete this job, can you write it up with pictures for the FAQ? There are a few diesels out there in the US (many more in Europe) and this is of interest.

Sure thing! I've been documenting my coversion and working on a website at the same time. Should have everything ready this week.

Thanks

Jerry

I'm getting ready to do this to mine as well after I finish up the rebuild. The hose that goes up from the thermostat housing and over the engine to the oil cooler looks like the best candidate for heat exchanger. should have good full time flow.
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-------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '82 Mercedes 300SD for sale