Coolant Mysteriously Disappearing

[JEBalles]

About two months ago, I installed a Greasecar vegetable oil conversion kit in my 1983 240D. This involved splicing into and adding coolant hose. After installation, the car was run, coolant added, run again, coolant added again. About two weeks ago, I noticed my coolant level significantly low, filled it up again. Last night, I topped it off again. I don't drive too often, maybe 50 miles a week, maybe less. I can't find an obvious leak, I was told maybe it could be a leaky head gasket. How would I be able to diagnose that?

[Gurkha]

Under hard acceleration or when you start up the car, do you get lots of white smoke, if you do, that means its a leaky head gasket.

[rrgrassi]

You could still have air in the coolant system. Also check your radiator and your veg oil tank for coolant. Those HIH setups can leak, and tracing it is a PITA.

Since the leak started after the VO kit, I would start there first.

[Brian Carlton]

The first thing to do is to get the device that pressurizes the cooling system. Then, search for a leak..........sometimes it's small and it takes a week to leak out one quart.

If you are positive that no leaks are present, it might be a good time to send off an oil sample to the lab. See if they find glycol traces in the oil. If so, the head gasket is compromised (not uncommon on older vehicles).

[jt20]

you should also be checking your coolant level at operating temperature and cold before startup. You will get 2 very different readings.

Plus now that hoses have been added, you are allowing for more expansion at warm temps = coolant level in reservoir appearing low

[winmutt]

He doesnt have a reservoir. What temps are you running?

[jt20]

good call, thanks.

where does the overflow tube go..? drain to ground?

[tankowner]

Originally Posted by winmutt

What temps are you running?

---> x2

Also, check the simple things first. Check your radiator cap to be sure that the rubber gasket inside is not brittle and falling apart. If it is, your system may not be pressurized and your coolant maybe boiling off.

If you want to make sure you don't have a leaky head gasket - drain your oil to make sure there is no coolant in it - the notorious milkshake look.

If nothing turns up there, then its probably your WVO set-up. Are you running HIH?

[Oracle12345]

Originally Posted by jt20

good call, thanks.

where does the overflow tube go..? drain to ground?

yeah, you have an what is called an open system cooling system.

Check all radiator hoses, area between block and head. if its not there the leak is internal so it could be the heater core which is found by having wet carpeting that smells like coolant. Also check the radiator

[barry123400]

If you have a heat exchanger for your vegatable oil it is imperative to make sure the coolant is not mixing with your fuel. Actually should have an aftermarket water separator anyways.

[JEBalles]

I already checked the vegetable oil tank, no leak, no smoke either, I looked up other signs for a leaky head gasket, no oil in coolant, oil looks fine, no smell from exhaust. No wet carpet either, cap's fine, and I just got the car in april. I never checked the coolant, but I never experienced any overheating or anything to make me feel something could be wrong. How would I check an internal leak?

[DeliveryValve]

As Brian Carlton stated earlier, get a pressure device and put the system under pressure. The other quick thing to check is your veggie fuel filter. Unscrew the bottom drain and see if anything other then veggie oil comes out. (warning... by doing so you'll introduce air in the system so make sure you hand pump the air it out afterwards) If you see something different it could be one of the internal o-rings or veggie line is compromised.

[JEBalles]

I checked the filter, just oil. how much is a pressure device? I have a vacuum pump, will that work?