could a bad/old radiator cap cause semi-overheating problems? ive tried everything else already, check for leaks, bleed the system again, made sure the fan worked, ive done it all. its starts to semi-overheat at crusing highway speeds.

what do i look for when buying a new one?

just go to autozone and pick one out? is there anyway by just looking at my current radiator cap to see if its bad?

 

i know you said you did everything.. but did u replace the thermostat?

 

I'm having the same problem. Anyone wanna shed some light on this topic.

 

first, drain your coolant, flush the radiator, then refil with fresh coolant/water. If that doesnt fix it, you can try pressure testing your rad cap. you can buy or rent (i think) the tester at pep boys. if your caps bad, get a new one. If that doesnt fix it try replacing your thermostat with either a stock one of a mugen one.

Is your engine stock ?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dfwtx &raquo;</TD></TR><TR><TD CLASS="quote">could a bad/old radiator cap cause semi-overheating problems? ive tried everything else already, check for leaks, bleed the system again, made sure the fan worked, ive done it all. its starts to semi-overheat at crusing highway speeds.

what do i look for when buying a new one?

just go to autozone and pick one out? is there anyway by just looking at my current radiator cap to see if its bad?
</TD></TR></TABLE>

If you are running warm at highway speeds, forget the fans. They are only important at either a stop or VERY low speeds. Also, chances are the radiator cap is not at fault. Generally, freeway driving keeps the coolant pretty cool, since there is abundant air flowing through the radiator to keep things cool (even on hot days). So the need for the cap to keep things from boiling over is not a concern. There are, however, some problems that can lead to running warm on the freeway. First and formost, make sure you have enough coolant. And make sure you are not losing it. Loss of coolant can be a sign of a leak OR blown head gasket (which, in and of itself, can also cause overheating).

Another common cause of freeway overheating is the radiator itself. If the radiator is clogged due to a large scale buildup, insufficient water will be able to flow through the radiator. Furthermore, that scale acts as insulation, impeding heat transfer. You might want to look into this. If you pull your radiator cap off and see alot of deposits, then chances are, this is the problem. But regardless, look into this. The first thing to try would be a flush. Try connecting the radiator to as strong of a faucet as you can and run water through it. This might take away some of the deposits. Also, you could try draining some of the coolant and using a flush such as that available by Prestone. This may also remove some of the scale. Just make sure you flush the system out well after using the flush in order to get as many of the deposits out as you can. If neither of these helps OR is scale is excessive, either have it cleaned by a radiator shop OR replace the radiator.

The thermostat can be another problem. Thermostats often get sticky or fail altogether when they get old. And they can get stuck in an almost closed to partially open position. This can cause overheating either always (if the thermostat is almost completely closed) or only under hot conditions and/or heavy engine loads (if it is partially open). The solution here is to replace the thermostat. In fact, given the relatively low cost of a new thermostat (~$20), just replace it anyway. You don't want to risk a serious overheat over such a cheap part, do you?

Water pumps are known to go bad, too. I have heard of a few cases where the impeller has been completely corroded away. If this happens, coolant will not flow. And overheating will happen. But this is unlikely. And chances are, this is not a problem, especially if the pump has been recently replaced. However, if turning on the heat does not bring the temperature down (and coolant is full), then this is something to look into.

Once this problem is resolved, make sure you check and change your coolant frequently. The cooling system is perhaps the most neglected system in the entire car (even by owners who are religious about other routine maintenance!). And this is why cooling system failure tends to cause such catastrophic problems.

 

A couple more things. For whatever reason, some bumpers have plastic pieces covering some of the holes in the radiator cowl, either partially or completely. And this will certainly reduce airflow through the radiator. This is most common on replacement bumpers. I don't know why they are there. But they are easy to remove. All that is holding them in is a small plastic tab on all sides. In other words, they appear to be meant to be removed. So if they are there, remove them. Also, make sure the fins on your radiator are free of debris (bugs, leaves, trash, etc). Both of these things can certainly cause your engine to run warm. They may not reduce cooling capacity to the point that your car ALWAYS runs hot. But they can cause your car to run hot under difficult conditions (high temperature, etc).

 

im having radiator issues as well and i am in dfw i have extra radiator cap if u need it and i am about to replace my radiator hopefully today............i leak a couple of drops a day........ the only weird things is that when i get on it maybe after 4500 rpm my temperature gauge goes all the way to cold and then when i cruise/drive normal it goes back to normal what can cause that?........... sorry dont mean to jack thread but its related

 

fixed.............needed new radiator and fan was not working.....replaced relay no more overheating!