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    • #56699
      Stephen Myers

        My tiger had been over heating with a recently rebuilt engine (I didn’t build it) and I took the thermostat housing off and found that no thermostat had been put in. Could this have been the cause of my overheating or does it make no difference at operating temperatures?

      • #60610

        I was always told that running without a thermostat lead to sludge build-up.

        My MKI 260 with 4-barrel was running at 215 on a 75 degree day until I did the following, as suggested by the cooling article by TT and Chuck King.

        1. Had my stock radiator cleaned and repaired where necessary.

        2. Installed the Fairmont smaller diameter pulley.

        3. Installed a 14″ five-blade flex fan

        4. Blocked off the horn holes.

        Now my car runs at 185-190 on a 75 degree day, and my interior is also cooler and more pleasant to be in. Total cost: about $150.00

        Fred Baum

      • #60611

        Oh, yeah, I run a 180 degree thermostat.


      • #60612
        Stephen Myers
          quote CLEVITE:

          4. Blocked off the horn holes.

          Had not thought about that one. My radiator is at the shop being cleaned and rebuilt right now, should have it back tomorrow. Thanks for the tips!

        • #60613

          Also make sure that the inner spring is in place on the lower radiator hose. My Tiger ran hot all of a sudden and I could not figure out what caused it. After replacing/checking everything I found the lower hose inner spring had rusted enough allowing the hose to collapse at higher RPM’s and restrict waterflow! Eric

        • #60645

          And the replacement lower hose I got from one of the good suppliers didn’t have an inner spring, I had to use the one from the previous hose.

        • #60646

          Just a couple of quick questions. You said you’re overheating — are you actually boiling over, puking coolant? Without a thermostat, your engine should actually run cool, which affects gas mileage and does cause sludge build-up over time. I recently did my ’65 Malibu ragtop 283 SB at .030 over and ran around 250-265 degrees on it’s maiden voyage. But after 100 miles, it was down to 195 — the thermostat rating. A rebuilt engine will be tight and run hot for some miles; depends how you break it in. Don’t be a wimp — if the block has already been broken in, (i.e., is used; rebuilt or not), drive it. See what it can do.
          Second, have you run any kind of cooling system cleaner through the system? A reverse flush (pressurized with the engine at operating temp — requires a machine designed to do this) may clean out any schputz that may still be in the block/head passages. That the engine shop didn’t get before the rebuild. Once you have your radiator back, do that. You won’t hurt anything.
          Third, if you’re relying on a gauge to register “hot”, are you certain the gauge is accurate? And the sending unit? Easy to check.
          Good luck — the S5 is on jack stands and beckons me…

        • #60658
          Stephen Myers

            Okay I got a chance to my tiger for its first long trip this weekend. Here is what I had done up to that point.

            I got the radiator dipped and roded. When I got it back I sanded off the rust and painted it with the special Radiator Black paint from Eastwood being careful not to get much paint on the core.

            I put in a 160 degree thermostat and for fun I put in a new stock temp sensor I got from VB (this sensor read about the same as the previous one so I figure it is working properly). A couple months ago I was driving the tiger and it got so hot that it blew off the top radiator hose which also makes me believe that it is reading correctly.

            Driving between home and work the tiger now stayed cool at around 180 degrees. On Saturday however I drove it about an hour away on the interstate to do some Dyno testing. The whole way it was creeping up to 250 degrees but I made it there safely.

            One the way back it was the middle of the day and the car quickly got up to 250 after a couple miles on the interstate. I pulled off and took the highway home. On the highway it was able to start cooling itself down and I made it back with no problems.

            It seems that at fast engine speeds it is not able to keep cool. 1. Either the hose is collapsing like stated above. 2. The air is getting trapped in the engine compartment and so flow is obstructed. 3. Something I haven’t though about.

            Any ideas?

            PS: Wayne how did you know my name?

          • #60659

            Do you recall a Solex secondary diaphragm? That’s where I know you… BTW: how are the corn and the soybeans looking out there in Iowa this time of year?

            Back to your overheating gig. First off, a 160 thermostat is TOO DAMN COLD. Put a 185/190 in there. Second, the fact that you “blew” a hose indicates a poor coolant flow somewhere in the system: block, heater core, or, what a lot of people forget, the water pump. Did you run some coolant system sludge remover through or do a reverse flush? Even though your pump may not leak, it may not be working properly. If it was a rebuilt unit or a used one, that MAY be your problem. Do the reverse flush — seriously. I think you can buy the hardware kit at a Parts Plus/Auto Zone/Pep Boys/whatever. You can do it at home or take it to a radiator shop (someone who does cooling and A/C systems ONLY). I’m going to throw caution and self-respect to the wind and say you have a water pump heading south.

          • #60661

            Just a thought.You may have an air lock.I know this happened to me once but not blowing a hose like you.I would elevate the front when filling the rad and that should eliminate any air in the system.I know some cars are recommended to be filled that way.A Midas shop where I get the exhaust done will only fill the rad that way when the system was drained for any reason.

          • #60666

            Here are my short comments on some of the items mentioned on cooling.

            A stainless spring in the lower hose is an absolute necessity. Without it the pump will suck the hose closed at high RPM and that stops coolant flow. For some reason, auto stores have stopped selling springs. That sounds like a business opportunity for someone.

            Thermostats help cooling. A thermostat provides a restriction that increases the pressure inside the pump. The higher pressure reduces efficiency robing pump cavitation. Inside the block, higher pressure reduces steaming pockets at hot spots. So run with a 180F/185F thermostat.

            Your hose blew off because the clamp was loose. A good hose will take much more pressure than a 20lb cap.

            Block off all holes that allow air into the engine compartment that doesn’t go through the radiator. These are of course the holes at the horns, between the radiator and cross member etc.

            Re core the radiator with a modern serpentine core.

            Look for the many articles that have been written about cooling. Some can be found in recent Rootes Review By King.

          • #61014

            This might be comparing apples to oranges, but a friend had a Triumph TR3 with overheating problems. He removed the thermostat, and it ran hotter. It seems that the water was not staying in the radiator long enough to be cooled. His solution was to run a 160 degree summer thermostat year around. In south Louisiana, you can do that.

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