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Doc,
In the second picture you posted, is that kink in the lower hose? Or just an artifact of the picture? I don't think a kink would help any...
Doc,
I used a Geo Metro Radiator that is about the same size as yours and it is only a 2 core I think. It is imperative that the upper tank has an abundant water supply. The following sketch describes how to accomplish this. The modern day radiator is not designed like the old thermosiphoned radiator of past. Water pumps are sometimes necessary but also can fail when you least expect it.
Has never gotton hot.
I think somebody on these forums successfully used the exhaust flow to pull air through the radiator.
I find it hard to believe that radiator is too small. It's only an 8HP engine, and that radiator is bigger than the one on my 120HP motorcycle. I suspect water flow issues, or airflow issues.
The fuel shut off valve came from Maine Diesel, it's less than $10 but it leaked. I called them and the only guy that knows about Listeroids was out to lunch. I left a message, but he didn't reply. I'll try again this week. They use straight threads from valve to tank using a gasket and that seems prone to leak. I haven't tried using tapered pipe into the bottom of the tank and adapting that to the rest of the line.
I've looked at a lot of cooling plumbing systems on this forum. Do you remember specifically the ultimate one you refer to? Thanks, Doc.
[/quotDoc, here is the basic system:
Can you tell us more about your setup, such as what heatex you are using and some more exact dimensions of the runs to/from it? The reason I ask is that vapor in the tank and sudden changes in tank level indicate to me that there may be boiling occuring somewhere in the system. This could be caused by a flow problem. If there is boiling, the pressure changes this causes would push coolant out no matter where the expansion tank was attached to the system... As mentioned it really needs to be at the top to expell gas. Very little energy in thermosiphon, so any air at the top will kill the flow...
I am running a 10 plate 600 sq/in flat plate heat exchanger. Transfers heat great, but because it contains so little coolant, I had to place it really high above my engine to get it to thermosiphon well enough to transfer the heat at full load. My expansion tank is right at the top at the heatex inlet, and the coolant level only ever changes slowly(raises 1/2" from cold to full warm). I have had a problem with secondary flow where I overheated and that is when I got rapid changes in the tank and vapor as the engine reverted to hopper cooling mode and released the heat in little gulps of steam... My Avitar is a scale diagram of my system, here is a larger view.
Doc, how about a bleed/bypass hole in your thermostat; got One?? My cold water side is a 55gallon epoxy lined drum , the lines from the engine to and from the heat ex are ss hoses to stop vibes from failing the hoses.
overbore
Hi Overbore, I was trying to keep this unit dimensionally small so it can fit into my smaller shops. My small shops have 6.5" doors, not a lot of headroom. The thermosiphon wasn't working real well. When I pushed the engine with 3kw of load it appears that the thermosiphon couldn't keep up. I think that elevating the radiator would cure the problem but cause a headroom problem getting in and out of the shops. I have a circulation pump that I will install and I think I will regulate the temp with a PID for control of the pump and radiator fan, I just haven't got it done. I am not yet running a thermostat. I was definitely getting some hopper cooling mode, since I too saw a couple of gulps of steam and shut it down. I use an infrared temp sensor to check temps on engine and radiator. I hung an expansion tank above the radiator for test. I haven't made a permanent bracket for it yet. Hopefully I'll have it back up and testing by the weekend. Maybe the weather will warm a little, Doc.