Radiator Cap

Hi everyone, I'm new here. I just purchased a 2005 TRD that will need a little work. I'm a furniture maker, and I'm very good at operating on old machinery, but vehicles have never been something I've gotten into maintaining myself. I mean I change my own oil and stuff, and I have done some repairs, but psychologically speaking I feel overwhelmed by all of the components of vehicles and I'm an admitted novice, but I'd like to change that.

The first thing I need to do do is take care of my cooling system. I am experiencing very erratic temperature changes, which seem to vaguely correlate to the RPMs. But sometimes the temperature will shoot up in neutral and cool during acceleration, and then it seems to switch around to the opposite cause n effect. I can't really figure it out. What I do know is the engine is very hot and yesterday the coolant was boiling after a short trip of about 3 miles in which 35 MPH was not exceeded.

I've been looking around at the threads on coolant flushing and radiator caps and stuff and they're illuminating. I'm going to try to flush it this evening but I was curious about what type of radiator cap I should have. The one on there now is very generic, and it seems to be S Type (because it embossed with an S). It also says "16 lbs" on it, which I guess referred to the pressure limit. From the sound of it, on a 2005 I should have an N type cap though, what would tell me that other than the year?

If I flush it and change to the correct cap but engine temperature still goes crazy, what's the next thing to check?

 

I don't think a flush or cap will fix your problem. I would start by investigating the thermostat and water pump. When was the last time these were changed - or if at all? I can't remember if the 2nd gens had a timing belt or chain - but if you have a timing belt, something else to consider doing as part of regular maintenance (if it hasn't already been done). YOu'll want to do all of these at the same time, while you have everything apart.

If you change the water pump/thermostat - you'll be getting a maintenance item off your list and flush the system at the same time.

As for the radiator cap..... THe OEM cap I had on my 2007 leaked. Had it replaced twice under warranty. They both leaked. So, I ended up buying a cap from STANT that had a higher pressure than OEM. That worked fine.....

 

Being that you said very hot, and boiling, I hope that your coolant temp did not exceed 230, resulting in a warped head/s.

Have you refilled your coolant? Is there any oily residue in there? Is the oil milky?

Did coolant come out of the overflow tank and spray?

If your radiator cap is too weak/aged, then it won't keep pressure, and the coolant can boil at a lower temp.

A higher pressure one will increase its boilingpoint. No harm done, unless a part of the coolant system is already damaged.

 

X2 Stant is the way 2 go - I'd go with mfg spec pressure what every that might be

 

Is it speed related? If the temp needle goes to hot at low vehicle speed and cools to neutral at high vehicle speed, the fan clutch is probably slipping and needs to be replaced.

Note that once the temp needle rises to neutral, normal behavior is for it to stay at neutral. If needle then drops to cold when the truck is still running, you have a stuck thermostat.