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To help prevent overheating, especially during our summer months, we are thinking that the muffler and rear area under the cover needs to be completely covered with some sheet tin. We’re thinking that hot air from the engine was recirculatingand adding to the overheating we think caused the engine failure.
Also, in taking out the parts from the old GEX engine, lots of metal parts and shavings were found. No doubt it was put together filthy.
The fan housing from the old set up doesn’t have any fins. Thinking that this could result in uneven air distribution, is a dog house housing a better set up?
Mark, a dog house is most definately a better setup. If you are going oversize (as you are) you most definately should have a dog house. Not having the fins would certainly hurt. I personally think that you would best benefit (for the $) by putting on a remote cooler. Most VW TDs run all the stock VW sheet metal but there is no seal between the upper and lower halves of the engine as was on a stock VW. If you really seal the upper from the lower, then you would need to add louvers or vents in the engine cover. The “tin” between the upper and lower engine probably reduces the radiant heat from the muffler/exhaust but does not do much to eliminate convection. At speed, there seems to be so much circulation that getting new air to the engine is not a problem. But, this “new” air can be hotter than blue blazes coming off the asphalt as in Phoenix. I’ve noticed a big difference in engine temp running from asphalt to the (lighter in color) concrete roads. The engine compartment on my Daytona MiGi is very similar to the London Roadster (I believe that the LR’s body is mounted about 2″ more forward on the chassis.) After putting all the factory doghouse tin with the standard (but larger) doghouse engine fan on, I’d run it. Put on an oil temp guage or maybe a cylinder head temp guage and/or buy one of the infra red pistol looking temp sensors (about $35) from Harbor Freight. Then if it still runs too hot, then I’d put on a remote oil cooler with possibly a remote electric fan to blow across the cooler.
I bought a remote oil cooler for additional cooling, but finding space for it will be a challenge. The dog house shroud is about $90, an expense I wasn’t planning, but sounds like it will be worthwhile.
Mark, a few more thoughts. First, lets agree that the German engineers were pretty darn smart in their design of this engine. However, the average high temp in Berlin during the summer is about 70F. The average high in Phoenix the average summer high temp is 100F+/-. Your engine is going to run hotter (about 30F) than in northern latitudes. Plus, top speed for later 1600VW is about 80mph. For the non doghouse (1500 and smaller) engine VW advertised 75mph as tops. (VW, made major improvement in their oiling system with the (dog house) 1600 engine to allow better cooling. If I were moving to Phoinix, I’d definately put on a remote oil cooler. Hope this info helps.
Those remote coolers, the coils that look like a little radiator, won’t do much unless there’s a large amount of air running over them, so if you want them to do anything, you need a fan blowing air across them. There’s really not much room or space in the engine compartment for that and you will wind up plumbing it somewhere forward of the engine bay underneath the car or fender.
The tin, a forward fire wall, and a doghouse cooler with the larger oil cooler in it and more in the air flow, solved my overheating problem when my engine was rebuilt. And an oil gauge is a must to keep an eye on what’s going on.My mechanic neighbor picked up a fan to blow over the remote radiator-looking oil cooler. But finding space for it will be our challenge.
He’s also planning to install an oil temperature gauge. I have an oil pressure gauge already installed.
One shop wants about $90 for a dog house housing, plus money for the larger fan, total, maybe $150.
I need to learn more about a “forward fire wall”
I just cut a piece of roofing material (galvalume?) used to cover the top ridge of my house that was left over (I save all kinds of “stuff” thinking I will use it someday) – It has a few slits or openings in it to pass the throttle cable through and the fuel line on the driver’s side, and it was cut large enough to close off the front of the engine compartment (3′ or so long, 18″ or 2′ high, I don’t remember the exact size). Right now it is held on to the body by metal heat-proof tape around the top and side edges, should I have to remove it. You have to make sure there’s no obstruction to the fan opening, and I have a spacer between it and the fan shroud to make sure of that. If I decide to leave it there permanently, and I won’t really know if it’s doing anything ’till it gets back up to 90 degrees again, then I will put a few screws in around the top and side edges to fix it more solidly to the fiberglass. I was trying to close off the engine compartment from surrounding heat, and it’s counter-intuitive, because you would think there’s more air blowing into and cooling the engine if it’s all open, but the problem is, you may be sucking hot air into the fan which greatly lowers it’s ability to cool off the oil as that hotter air blows over the oil cooler in the shroud. And that’s the way VW designed it.In a VW the cooling air is supposed to come in through the rear deck louvers, in our case through the holes in the rear deck beneath the spare tire.
mrlmd40914.5950231481Marc, You’re right about VW engineer’s plan for air flow. I’d be interested in seeing some pictures of how you separated the air flow, upper to lower halves. But, we won’t know how well it worked for a couple of months.
My car came with the VW tin, and it was put back on after the engine removal/rebuild/reinstall, as recommended by the really good VW mechanic who rebuilt it and from what I have read. I sealed off the gaps between the tin and the body with that same metal heat-resistant tape and it is still sticking on there, so I do have a fairly good seal between upper and lower engine halves. One of these days I may buy the VW rubber gasket that fits in the stock car to see if that gives a better seal, but I don’t know if it would fit right because the VW bodywork has rounded corners, and my car has square corners on the bodywork in the engine compartment, but for now the tape is working. My 2 heater air outlets from the doghouse fan that are directed down to the heat exchangers are sealed off with plugs, that’s the way I got the car, no heater tubes, so now all the cooling air from the fan goes over the oil cooler. I sealed off the round openings where these tubes pass through the tin with small plates of that same galvalume screwed into the tin, then painted black to match.
One of these days I’ll try to get a pic posted of my temporary makeshift forward firewall so you can see what I did. And, like I said, I have no idea if this does anything for the engine temp until it warms up down here back in the 90’s, but it’s running great right now. My engine oil temps stay 170-190 depending on how long and how fast is my trip (don’t know how accurate the gauge is), the dipstick is hot but touchable, and if I check the pan with a laser infrared thermometer, the temps are in the range they are supposed to be.
One of these days if I can’t stand the freezing cold anymore, I may get a set of heater tubes and cut holes behind and under my seats, and install heat into the car. Then, if the weather gets really hot in the summer and my engine temps go up, I can always pull those tubes off the fan shroud and reinstall the plugs to get better air flow over the oil cooler.mrlmd40914.7394444444
It seems logical that if you plug the air going to the heater, you might get more air going thru the oil cooler, but doesn’t just turning off the heat do essentially the same the same thing? …and since you wouldn’t want heat in the summer anyway, is it necessary to take the hoses off and plug the fan outlets on an engine that runs hot or if you live in a hot location?
That was the way it was when I got it, there were no heater hoses and the heater outlets off the fan shroud were plugged. On my car, the rounded caps that the hoses should attach to underneath the tin (I don’t know what you call them), where they attach to the heater boxes, do not exactly line up and and the end caps don’t readily slip over them, so there would be air leaking out of that junction. So even if the heat were turned off by the floor controls and the flaps were closed, I would be losing cooling air. I would guess that if the heat were turned off in a car with all the hoses in place and not leaking, that would stop the air from the fan going through, but it might also tend to warm up the engine compartment (?) as those hoses might be pretty warm.
Without a great deal of work, I cannot easily get those end caps and the boxes to line up and fit right, I don’t need it now, so I’m not going to try and fix it.
I also drive with those flaps on the heater boxes wired open so air can flow in through there and then out the open aft end of the heater box, theoretically helping to cool off the exhaust pipe going through it.The cabin heater hoses were not hooked up on my London Roadster when I bought her. With the engine being rebuilt, I hope to hook up new hoses for our chilly winter mornings. In this desert, we really are in a land of extremes. It can drop into the 30’s or below at night in the winter, and climb above 115 F in the summer.
I certainly don’t need heat in the summer here, but au natural air conditioning doesn’t work, either.
I get to enjoy my TD replicas when the sun is up in the late fall, winter and spring. Once past May, driving without artificial air conditioning is really not an option here. Parked in the sun on a summer day, internal car temps can reach 140F! Even the sun smashing down on me at 112F is really too much to bear. She just won’t get driven too much at that time of year.
I’m kind of opposite of the rest of the country. I put my toys away for the summer and bring them out in the winter.
MGLondonRoadste40917.8023611111
The answer to my own question after further investigation is that closing off the heat with the floor levers does not stop the air from flowing through the heat exchanger boxes. They vent to the atmosphere when the heat in the car is off. I read that this is because the heat exchangers in the stock muffler setup are part of the cooling system and the air flowing through the heater boxes keeps the temperatures in the valve cover area down. ….Who knew?
What effect plugging the outlets on the fan shroud has is still unknown (at least to me).
Royal I have read the exact same thing about the air flow through the heater boxes helps to keep the area cool over the valve cover . I dont disagree, but my heater boxes are not hooked up to my fan and when i pointed my infrared thermometer at them they were much cooler than the surrounding bare exhaust. I do know when you run J pipes instead of heat exchangers, it is recommended to use industrial sleds. These are pieces of sheet metal that will fit between your J pipes and valve covers to help shield them from J pipe heat. I myself have the exchangers on with no air flowing through them and fan ducts plugged. I think the exchangers are shielding heat from getting to the valve cover and the plugged ducts are forcing more air flow over my engine. As a side note the industrial sleds I mentioned were used on industrial VW engines where no heat was needed. I have seen templates for these on the web for those who want to make their own.I suspect that using exhaust wrap on the J pipes would work as well as the sleds. I imagine you will get many schools of thought on plug not plug, flow the air over the exchangers or not flow. The VW gurus debate this stuff all the time, so I think its a owner choice thing.
Mike, Very likely you are right,- an owner choice thing. I am new (again) to VW’s having owned 2 about 40 years ago. So, whatever I say is probably something that I have recently read or something that I thought I knew that I learned on my other autos. I read a lot and tend to over study things which often means that I over worry about stuff that isn’t worthy. Roy
I do the same in the reading department Royal . It seems when you come across some information and think that makes perfect sense, then along comes some other info that seems to contradict the first. I do believe the German engineers knew what they were doing in the tin deparment for cooling and that it should be left intact. These forums are great and I learn something new every time I come here. These little air cooled engines amaze me in their basic simplicity, yet they have a well thought out balanced design. The parts are almost symbiotic, one that looks insignificant is important in the scheme of things. Mike N Scarlett40918.280775463
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