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Thermostat


Budtee
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I had a Turbo 1 in a Chrysler convertible a few years ago and replaced the head gasket. I seem to recall replacing the thermostat and drilling a 1/8" hole to allow a small amount of coolant to bypass during warmup. Someone recommended that but I don't remember where I got the tip.

I now have an 89 TC with the 8v Turbo 2 and will be replacing the coolant and thermostat when I get back to Pa in the Spring. Does anyone know anything about it and whether it applies to the Turbo 2? If so, I would appreciate any info on the exact location of the hole.

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I had a Turbo 1 in a Chrysler convertible a few years ago and replaced the head gasket. I seem to recall replacing the thermostat and drilling a 1/8" hole to allow a small amount of coolant to bypass during warmup. Someone recommended that but I don't remember where I got the tip.

I now have an 89 TC with the 8v Turbo 2 and will be replacing the coolant and thermostat when I get back to Pa in the Spring. Does anyone know anything about it and whether it applies to the Turbo 2? If so, I would appreciate any info on the exact location of the hole.

To be a little more specific... I read about this constantly in the 'K' car circles. They seem to think this is the magic bullet 'hole' that cures everything about overheating, blown head gaskets and warped cylinder heads. That is going a little far, in my opinion.

To begin with, the hole should be as close to the top of the thermostat in relation to the way it is mounted in the head (vertically). With the hole in this position and the thermostat in place, when the engine is started cold, the thermostat is fully closed and passing no coolant except the small amount passing through the hole. The rest of the coolant circulation flows through the by-pass hose and back into the engine block and head. This allows the coolant to warm up more rapidly and yet maintain a rising temperature also at the thermostat. Without the hole and the flow through it, coolant would not affect the thermostat as evenly and therefore, when the thermostat finally opens, cause a significant change in the coolant reaching the engine block because all of a sudden all that cold coolant in the radiator would be let loose. Think of it as standing in the shower, under nice warm water, then suddenly switch off the hot water, all that remains would be that shockingly cold water on your body. The engine experiences a similar 'feeling'.

The hole also helps to eliminate any air trapped in the cylinder head especially after draining or flushing the system. Air trapped at the thermostat would allow the coolant to reach boiling temperature long before the thermostat feels the heat of the coolant, which many of you have experienced when flushing the system or replacing the thermostat.

I hope this fully explains the desire on the part of some people for the hole in the thermostat.

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When replacing a t'stat, and to prevent possible future problems of overheating your engine buy a failsafe t'stat. This t'stat is designed to fail in the OPEN position thereby not causing possible engine or radiator damage by failing in the CLOSED position and overheating. They cost a few dollars more but are worth the price.

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Many years ago I was road racing a 'cuda with a lightly modified 340. After a few laps it would start running hot (don't ask about the brakes, or lack thereof). Some genius suggested removing the thermostat, which we tried - and at first the car ran cooler, but then much hotter. Finally we drilled a small hole in the thermostat - problem solved.

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Budtee, you shouldn't need to drill a hole in the thermostat flange, if you buy one with a jiggle pin valve. Most Japanese and American cars have been using this type for years. Remember, the copper pellet of the jiggle pin should face the engine and it should be at the top of the installed thermostat ( twelve o'clock position). Check www.RockAuto.com for thermostats for your engine. They have many different brands, operating temperatures, and some with jiggle pins (MotoRad premium).

I hope this helps.

Edited by rmtroutman (see edit history)
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Don't try to save a few dollars when buying a thermostat, replace it often as I do, every 3 years and then, ... perhaps save your engine and hundreds or thousands of $'s in repairs. Use anti-freeze that also contains good lubrication and it is far less likely to sieze-up or get stuck and leave you stranded somewhere. With the TC, ... 180 degrees is the best all around, I believe, .... but check too with other members to confirm.

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Here is the Blue Service Manual for the 2.2 SOHC which looks like the thermostat does not have the 'air vent valve'. In the red manual they do show the thermostat with the 'air vent value' for the 3.0 L. Looks like they suggest the 195 degree thermostat.

post-89473-143142991374_thumb.jpg

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I always thought the hole in the thermostat of the 3.0 was a vent hole, and it made it easier to fill with coolant. The 2.2 has a plug above the thermostat, and when removed, creates a vent. When the Service Manual calls for a 195 degree, that is what I would use. Any of the sending units and control modules are set to operate at the higher temp. Also when the engines run hotter, they stay cleaner inside.

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Alferi recommends 180 degree thermostat. Rock Auto says 195 is OE. (They also have the180) I would like to get some more opinions on which is best to use.

alferi is no expert. That is obvious. B&B is correct. Chrysler Corporation prescribes a 195 degree thermostat because with such a thermostat, the engine runs cleaner and emits less pollution. Engine coolant temperatures are safe at 220 degrees as long as the cooling system is clean, there is at least a 50/50 mix if quality antifreeze and water. There must be a 16 lb radiator cap, able to maintain that pressure. I drive my cars, 2.2L, 2.5L and 3.0L in desert temperatures some times as high as 126 degrees F.

I have never had any engine problems related to coolant temperature.

i think you have all been sufficiently informed and would be wise to quit worrying. Just make sure your cooling systems are up to doing the job they were designed for.

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  • 2 weeks later...

HA! , ... was a slam really needed here? .......... I just picked up Hemi Andersons's thread. I want to be kind here but will respond soon to Hemi' 'A' 's comment,.. in a way that is 'above all', ..... fair to the TC Members and guest viewer's.

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