new guy here, not a professional mechanic but pretty handy with a hacksaw and sledgehammer. before i joined i read back through post history to see who may have had the same sort of issue and i've found one or two that were sort of similar but wanted to post the specifics of the problem i'm having and see what the general consensus is. so here's what i've got:

'99 dodge neon, dohc, stock, about 150 thousand miles. about 8 thousand miles ago, the water pump decided to lock up which took the timing belt with it. since it's an interference engine i had to do the whole 'mill the head, machine the valves, etc' thing but on the bright side i got a new water pump, timing belt, valve job, seals and all that great stuff. so now that it's starting to get nice and toasty outside we've started having a problem with the car wanting to get hot under load. if i get much over 60mph on a relatively flat stretch of road, the car starts to get hot. if i back off the speed a little bit then it cools down a little but still warmer than usual. i can go 70mph downhill (not much engine load) without it warming up and if i do about 45-50mph or so uphill the engine starts getting hot. if i'm in pretty slow stop-n-go traffic the engine is warmer than it should be, but it doesn't overheat.

1. i've replaced the radiator cap, no change.
2. i've flushed the cooling system (which was very clean since it was flushed with the water pump change 8k miles ago), no change.
3. i've checked the fans, they are working as i'd expect them to.
4. i've replaced the thermostat twice, no change.

while trying to determine the cause of the problem, i've discovered that my coolant reservoir has a crack in it and isn't holding coolant. i'm wondering if this may have fed some air into the system as it tried recovering coolant, and air in the system could explain what i'm seeing. however, i'm also wondering if the tranny (auto) is getting hot and the tranny oil going through the cooler is heating up the radiator.

so, that's what i've got. any ideas, suggestions, opinions, etc?

thanks in advance.

 

Clooged or bad radiator.

 

thanks das, it looks like i'm going to yank the rad tomorrow and check it out. i hadn't done that yet because i figured if it was clogged i'd be having problems regardless of speed, but that's just my inexperience with radiator problems. i've done some reading up on clogged radiator symptoms since reading your response and it looks like you're probably right on. i appreciate the pointer, and i'll let you know how it goes.

thanks again.

 

just a quick update on this. i popped a new radiator in and that did it.

thanks again!

 

Just a reminder though that if you have a cracked overflow bottle you will indeed start adding air into the system and creat problems for yourself as well so replace that as well if you have not yet.

 

Good to hear you are up and running again.

 

Damn those radiators *heh*