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Mrlmd..just curious if you picked up the infrared thermometer and if so what temp reading did you get as compared to your gage? I also am curious if you checked your thermostat controlled flaps on your shroud to make sure they are opening. Mine does not have the thermostat installed and the flaps are always open.
I checked my sending unit by putting it in boiling water for a 210?F reading.
The operating temp. lowered considerably when I got rid of the “bag of
snakes” exhaust muffler. It was trapping heat in the engine compartment. I
replaced it with a single pipe “GT” style ( EMPI # 3487 ) that allowed air to
exit out between the bumper/rear deck and the engine. Proper belt tension
and timing, plugs, rubber plug seals ( I had mine wrong ), 89 octane ( I
know, but I do it anyway), and Classic Car Motor Oil 15-40w with lots of
ZDDP. At 95?F OAT, I went 40 miles at 60 mph with a 210?-220? reading.
The sender is an oil sump plug replacement. Rollie
The plug on the relief spring will give you a accurate reading of what the oil temp is in the oil journals. Mine is set up that way and works fine. The higher the resistance the lower the temp, the resistance gets lower as the temp increases, getting to zero at max limit. If replacing the plug be careful to make sure you have a good seal, because you can be seeing up to 60 PSI. and can cause a leak. If you are sensing the temp at the wrong part of the engine then the temp will vary, higher or lower. As long as you are maintaining good oil pressure you are probably all right. Synthetic oil can be dangerous on VW, according to Berg, he said some of the full synthetics have a problem transferring heat, since it does not conduct as well, it was designed around water cooled engines(awhole different game). REMEMBER ‘VW’S ARE OIL COOLED” ALSO. I use a synthetic blend 20 w 50 Castro and with the laser thermometer it shows about 190 for oil temp, same as the Gauge. The blend is a better heat conductor, and you need the oil to carry the heat off of the heads, through the rocker covers. also you need the thermostat and vanes to get the proper airflow. I have been playing with VW’s for 40 + years and found the engines last longer with the whole thermostat system, if the fail it is in the open position. If they take too long to warm up that increase engine wear and expansion of the aluminum takes longer causing leaks. it needs to expand to seal properly. I have always run the whole thermostat system. Also you need to try to separate the upper and lower end with sheet metal, just as VW does, this keeps hot air from being sucked in at the cooling fan intake. This means that you need some ventilation on the upper engine compartment, when you have it sealed. The Germans are pretty sharp guys and the put all that stuff in for a reason. The racers don’t sit at lights for a long time and are not in stop and go traffic, so they don’t use all that stuff, mainly for weight reduction. This is just my experience and 2 bits worth. The thermostat really does prolong the engine life.
I’ve done a few experiments trying to cool off my car –
First – I made sort of a
firewall in front of the engine closing off the opening down to the transmission, not air tight, but intending to block some road
debris and leaves. etc from getting into the fan, keeping the sheet
metal a good 3-4″ away from the fan opening. I rode about 7-8 miles, then my temp gauge went up over 210-220 so I stopped and took a few laser readings to see what was happening. This piece of sheet metal
got really hot after riding about 10 miles, and I think probably heated
up the air drawn into the fan and probably inhibited it’s cooling
ability by passing hotter air over the oil cooler. My engine case temp at the sending unit was up over 230. I removed that whole firewall thing and left the front open for better air flow. The engine temp came right down after riding with that removed.
Then, since I do have the tin at the sides and rear of the engine, I have taped it off to the bodywork (fiberglass) to separate the lower hot half of the engine from the upper half. This seems to make a big difference in my engine temps, at least as read on the dash gauge- it takes about 5 miles of driving for it to go up to 170, stays between 180-200, no longer goes to the 230-240 range on the dial.
I have been checking my engine temps with the $20 laser infrared thermometer from Harbor Freight at various locations, to see how it correlates with my dash gauge and side to side on the engine. The oil pan and plate read about 170-175 or so, 20-30 degrees cooler than the site of the oil temp sending unit at the relief plug site at the left rear of the engine. The valve cover on the right side reads 15 degrees cooler than the one on the left. The oil temp sending unit and surrounding metal on the case in that area reads 15-20 degrees hotter than the reading on my gauge. The tin around the engine gets hot- 150 degrees or more, from the mufflers and cylinders underneath. I thinks the air coming up through there is what what heated up my previous firewall, maybe the firewall and sealing off the tin as per VW’s original design is the best combination.
Yesterday I went for a 15 mile ride up to 60mph, no overheating, parked for about a half hour in the shade (95 ambient temp), and the car was a little hard to restart, had to try it 3-4 times ’till it started. It ran OK, then just died after driving about 1/2 miles and would not restart or catch for anything. I opened my rear cover, started measuring the temp of everything with my new laser toy, and my metal can fuel filter and fuel pump were about 140-150, the carb 130-140 degrees, the engine tin 150-155. I was wondering if I just had a vapor lock in the fuel pump or filter as everything else seemed to be fine. Luckily my GF was home and she brought my other car and tow bar (everybody should have one of those, the best accessory you can buy for $90–100), so we dragged it 15 miles home. Of course as soon as it got there, it started after one or two attempts and runs fine, so vapor lock seems a good possibility. I’m going to redo the placement of my fuel filter to get it away from the engine if maybe this had anything to do with it.
I’m also thinking of keeping the flaps in the front of the heater boxes open to allow air to flow through these when moving, maybe that would aid cooling off underneath a little bit (I have no heat installed on this car).
I have no idea if I have the thermostat controlled vanes under my fan shroud, there’s no way to look in there, I’ll have to ask the mechanic who rebuilt the engine.
Another option to aid cooling in the engine compartment is to put some vents or louvers in the top or sides of the engine cover (false gas tank) but this would detract from the look. Mine has 8 oval shaped holes matching the wheel over it as the only source of rising hot air escape.GrandpaJoe…that is a great summary!
Thank you!
Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica RoadsterIf you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)
mrlmd,
The easiest way to check if the flaps are installed in the fan shroud is to look at the base of the fan shroud near each side and see if you see two screws (like the engine tin screws) there. If so, you most likely have the fan vanes installed. The second way is to either look or reach below the fan opening and see if you can see or feel the long linkage along the bottom of the fan shroud. It’ll have a spring from the linkage to the shroud. The third way would be to remove the short engine tin on the bottom right (Looking from the rear) of the engine and see if you see the thermostat. That’s the reason one of the lower tins is in two pieces. It gives you the acces to the thermostat. Hope this helps.newkitman40773.6020717593
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The ShackI can’t see or feel anything under my fan shroud, it’s the doghouse shroud and it’s completely sealed up underneath, can’t see anything with a mirror either, and I sealed up the tin to the body with some metallic heat resistant duct tape to try and keep the heat from rising into the engine compartment and that seems to be working. I don’t feel like I want to remove all that now and remove the engine tin on the right side to try and look in there, at least not at the moment. I may try and get some fiberglass insulation, like pipe wrap, and stuff that in there instead of the tape, or cover it with the tape.
I was told that a new engine, or a totally rebuilt engine, runs a little hot ’till everything wears in, so we’ll see what happens in the future.
I relocated my metal fuel filter to a cooler location on the side of and slightly in front of the engine, before the fuel pump intake, from the spot it was in on the outlet side of the pump close to the fan shroud before the carb, so maybe that will avoid a possible vapor lock in the line.
The car is a blast to drive but the uncertainty now of having it not start when it’s hot, or possibly overheating, is taking some of the joy out of it right now. Good thing for having a cellphone.I have my fuel filter mounted up front on the opposite side of the car from the brake master cylinder. Included a shut-off valve ahead of the filter so I can turn the fuel off when I’m changing the filter. I don’t want one of those little fire starters anywhere my coil or distributor if ya know what I mean.
Allen Caron
VW based 53MGTD - "MoneyPenny"
"If one thing matters, everything matters" - from the book The Shack
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