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I have a over heating problem. I have replaced the water pump, thermostat, upper radiator hose and the coolant temperature sensor. They were all in need of replacement, but my car still over heats when going up hill only. I checked the fins on my radiator and there are three medium potatoe size areas where the fins are badly bent. Could this be causing my over heating problem?

My other question is if the fins are bent can this cause the transmission fluid to get to hot. My reason for this question is because when the car gets to normal operating temperature, but I have been driving for some time my transmission during first and second gear shifts hard. When the car is cool it does not?

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3 Answers 3

Firstly, you don't mention what car you have, which can help with diagnosis as we may be able to point you towards known issues with certain models.

Bent or missing fins will cause the radiator to work less efficiently than normal, but that sounds like a fairly small area, so shouldn't be causing you a major problem. It is probably worth flushing the radiator out if you haven't done so already.

The engine radiator is usually totally unconnected to the transmission fluid, so I doubt the two problems are related. Do you have a transmission cooler? If so, what condition is that in? Have you checked the condition and level of the transmission fluid?

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Small areas with bent fins on radiator are not a big problem.

The other causes for overheating could be coolant fluid needs replacement (its cooling properties degrade over years). Also I would inspect inner surface of lower radiator hoses - see if they have traces of mud or other flow obstructions. My cockpit radiator suffers from that - its clogged with anti-leak mixture I used and needs replacement, until that it is really working at 20% of its limit.

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Bent cooling fins can most definitely increase engine running temps considerably; and you do have a significant amount of blockage. Only a few years ago my 23 year old pickup needed a new fan and fan clutch. I had grown accustomed to the temp meter running mid scale to slightly above mid scale, rather than below mid scale, and I had just chalked up the hotter running to engine aging. With the change of fan and clutch the temp characteristics did not change. Shortly after I replaced those items, the radiator developed a leak. So I replaced it and, with a fin straightener I bought along with the radiator, I straighened all fins, including in the AC exchanger through which air had to travel to arrive and be sucked though the radiator heat exchanger. I was amazed to find that the vehicle's normal operating temp returned to the same, characteristically low (below gauge mid range) operating temperature that it showed when brand new. Snce then there has been not the least occurence of hot running, even with radiator substantially underfilled.

So do make it a practice to periodically inspect and striaghten fins. Also, take water hose and nozzle and flush/back flush insects and debris from those fins, too.

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