overheating problems

[murrayarnold]

Hi guys.
I have found that the Spider I have seams susceptible to overheating. I have a friend up the coast from me with several spiders and he has told me they always suffer from overheating. I have even removed the thermostat (no simple job) to let the water run freely. I have Para-flu in the cooling system. The radiator is clean and not obstructed by spotlights or any such paraphernalia. The temperature still goes up to normal and it’s not even summer yet. And it does get hot here in summer.
I have added an additional switch inside the car so if i hit any hills or traffic I can turn the fan on early.

Does anyone have any idea about what may cay be causing this and if there is a cure. The engine is not in great condition, but not the worst. There is slight back pressure as the car needs new rings I guess.

[ventura ace]

MurrayArnold
What year is your spider?
What engine? Stock or modified?
The thermostat that you removed -- was it in the cylinder head or the external type?
Is your heater connected and functional? Or is the water flow bypassed to the back of the engine?
You mentioned that the radiator is clean. Are you taling about the outside or inside or both? Has it been flushed out or professionally cleaned? Has it been painted (painting with the wrong paints will prevent proper heat transfer)? When your car is warmed up, does the whole radiator get warm -- feel it with your hands in different areas to see if it is hot all over or just in certain areas?
How old is your water pump? Are you sure that you are getting good water flow?

My experience is with 1438cc, 1608cc, and 1.8L engines, all with the intermal thermostat. The 1438cc and 1608cc always cooled nicely. The 1.8L with the internal thermostat, I find that I need to open the water flow to the heater a lot of the time to help circulate water to the back of the head, or else the water temperature indicates a little on the high side. So, I drive around about half the time with the heater water valve open. This presents no problems, since I leave the heater air flow flaps closed so it won't cook the cabin. I've been told that this would be less of an issue with an external thermostat, but I can't verify that since I've never used one.

Alvon

[murrayarnold]

Hi Avlon.
First of I have flushed the system and put in para-flu. I have a brand new water pump and so on.
Its a 77 1.8 with the thermostat in the outside pipe. Or at least until i took it out. There is no airlocks and as you said i end up with the heater on and roasting the cab.
God knows.

Someone suggested flushing the water system again with baking soda. Dont know if there is anything in that idea. And apparently there is a bolt in the block under the exhaust that i should undo to drain it.

[kmead]

So how did you go about removing the thermostat? What is the current hose routing? If this isn't done properly you can create problems. In addition removing the thermostat can make it so the liquid in the cooling system circulates so quickly through the radiator that it doesn't shed much heat and as a result the overall system will fail to cool properly.

I would also reiterate the question about how you know the radiator is in good condition. It is quite possible that it has blocked passages, thus the previous poster's question about localized hot and cool areas.

Thermostats are there for a reason, deleting them is not the way to ensuring a properly functioning system. If the car is in fact overheating and not suffering from a defective sensor or gauge then there is a blockage, bad water pump or some other defect that needs to be rectified.

[murrayarnold]

thanks for the ifo.
It all makes sense what you said. I never looked at it that way about the water flowing to quickly. But your right. I will go back and kick the ass of the person who told me it was a good idea and then done it. And he is meant to know spiders, lol.
Ok thanks for that once again and i will get on it tommorrow.

I have the system to flush in my TR6 also so I will do the both at the same time.

Thanks guys.

[htchevyii]

Is it actually getting hot, or just to normal? Is the fan comming on? Maybe it is normal? You could also check the temp with a mech gauge if it doesn't seem that hot maybe it isn't reading correctly. Good luck.

[racydave]

Since you are getting good heat thru the heater core, its not an air pocket. Thermostats really help warm up the engine, and they run alot better at operating temperatures too. If there is still a "problem" then its either incorrect temp reading, or poor flow thru the system. I would rather guess it would be restricted inside the Radiator than a water pump thing. A laser temp gun would tell alot about how the radiator is working. Also a good maintenance would be to blow compressed air back thru the radiator from the fan side.

[ventura ace]

thanks for the ifo.
It all makes sense what you said. I never looked at it that way about the water flowing to quickly. But your right. I will go back and kick the ass of the person who told me it was a good idea and then done it. And he is meant to know spiders, lol.
Ok thanks for that once again and i will get on it tommorrow.

Hold on, now. It is correct that removing the thermostat will make your engine run too cool, assuming everything else in your engine cooling system is working properly. That's the purpose for the thermostat -- to regulate (slow down) the mass flow of the coolant so that the engine can reach the optimum operating temperatures. Your engine cooling system was designed to have adequate heat transfer under some rather extreme conditions. In other words the radiator cooling area, the fan air flow, the water passages in the engine, etc. were all designed to allow the heat to be transfered away from the engine on the hottest of days, when running with the engine with the most demanding loads. The coolant thermostat is one part of this complex cooling system that helps regulate that temperature so that the engine is not 'over-cooled'. The electrical thermostat switch and fan are another part of the temperature-management system.

If the car is not properly maintained through the years, then this complex cooling system no longer works the way it was intended. If the coolant fluid is not flushed and changed regularly, scale will build up on all the water jacket walls in the engine, and reduce the heat transfer efficiency. If the radiator is partially blocked, by contaminants plugging up the inside, or by bugs or excess paint covering the fins on the outside, its heat transfer efficiency is compromised. If the water pump impeller is corroded or the fan belt slips (or wrong size pulley, or poor design water pump, etc.), lack of adequate water flow will reduce the heat transfer efficiency of the system. To fix an ailing system it is important to maintain these items discussed above.

All too often, someone will ignore these important issues and band-aid the system by removing the thermostat or wiring the fan so that it runs 100% of the time. All this does is make the system transfer heat to its maxium effectiveness, under its crippled condition. The goal should be to un-cripple the cooling system, and use the thermostats to control the system temperature, as orignally intended.

1) Before taking any corrective measures, be sure that your temperature gauge reading is not the problem. Use another temperature sending unit, or anothe gauge, or use an optical temperature measuring device to confirm temperatures. Are you losing excessive water through the overflow tank? Does it smell overly hot? Make sure it is really a problem.

2) When starting the car and letting in warm up, use your hand to feel the temperature of the radiator (be careful!!-- there's things close by that can mangle your hand!). Feel around in all the areas you can reach. It should heat up fairly evenly all over, starting from the bottom to the top. If there are warmer can cooler regions, this suggests that the radiator has blockage inside.

3) Be cautious with using different fluids and chemicals in your cooling system. Some are not compatible with others and will cause congelling and other serious problems. Flush the system thoroughly with water, with the engine running, and heater open, for an extended time. Then use a commercial flush chemical to attempt to treat the scale, then flush thoroughly again before adding your coolant.

4) Have a radiator shop check your radiator to give you a ruling on its health.

5) Verify that you have good water flow from your pump. Break a line loose and see if it is pumping water out at a fast clip. It should.

6) Flush and change your cooling system on a regular basis. Most manufacturers recommend every 2 years.

Alvon

[racydave]

I remember GM had a heat quality issue on some heatercores, and the fix was an orifice to slow down the flow, and make it hotter.

[murrayarnold]

Hi Avlon.
All good info there. Thanks for the effort mate. Well i started the process this morning on my Triumph. I have an auto shop 50 yards from my door and will go for the recomended procedure first. I will tale the botttom hose of and flush until clean water comes out. I will then add the radiator flush fluid and take the car for a 20 mile drive. I will then reflush and add a 50/50 paraflu mix and see what results I get.

I think the basic method first is the correct way to go. I will also look into getting a new thermostat in the interim.