SmCross

Here's what I know - Hopefully Someone here will have some insight for me.

1992 SC300 w/ 121,000 miles.

I drive very little but had noticed that any trip longer than 30 minutes we would begin overheating. I tested and replaced the thermostat myself, and had a local shop run a pressure test through the cooling system. They ended up replacing the hoses and a seal and said that (aside from a tiny pinhole leak that they weren't really concerned with) the radiator was fine. I ran some stop leak through the system just for good measure and called it fixed. (On a side note, I'm wondering now about the wisdom of using stop leak..?? )

I resumed normal use of the car, the car would get hot during longer trips but wasn't overheating for about 2 months. Now, In the past month the car has begun overheating badly again. In just the 10 to 15 minute drive from my home to work it will overheat. When I get out of the car after a short trip for groceries I can actually hear boiling in the radiator.

It's not losing fluid, as far as I can tell there is no leaking. The car does NOT overheat when idling. The lower radiator hose that's connected to the water pump and thermostat is cold when the upper radiator hose is real hot.

No, there is not any white/gray exhaust. There is no water in the oil or vice versa. The engine sounds and runs as strong as ever.

Now I called the Shop back that did the hoses/pressure test and without reminding them of the previous service they had done I quickly explained that I was concerned it might have a clog and would like to check the price of having the cooling system flushed. simple. The Guy immeadietely said that My Radiator was most certainly "coming apart on the inside" and it needed to be replaced.... When I told him that his shop had just told me the radiator is fine about 2500 miles ago he insisted that alot can change in 2,500 miles. Ugh.

I meant to keep this short, sorry. I don't want to start by jumping into the worst case scenario repair - and If its a Head Gasket I can't afford it anyway - so What is my first best option? Flush the coolant system? Replace water pump? If I need to replace the radiator fine - I can do that myself - But I'm not ready to scrap the radiator when I was told less than 3000 miles ago that it was basically fine.

I've already tried kicking the tires and cussing at it.

Thanks in advance for helping a lady in distress!

0435

If it was headgasket it would blowsmoke and run funny.

Sounds like a waterpump/tstat/loose clamp issue.

good2go

iTrader: (6)

A few thoughts come to mind.

Fan clutch is failing

or

as mentioned above, waterpump (assuming you have eliminated the T-stat)

or

restricted airflow to radiator caused by clogged or bent AC condenser and/or radiator fins. A broken fan shroud would contribute too.



EDIT: After re-reading, this part makes me lean more towards the waterpump.

Does the lower hose stay cold even after you've been driving a while and it's started overheating, or did you only test it with the engine just reaching operating temp from an idle?

002is300

I had the similar problem,I had one mechanic tellin me it was the radiator plug,thermostat,fan.....but actually turned out to be the water pump,and when I got the car about 2 months ago,the owner supposibly had changed the water pump,but it was no good.it overheated about 20min after I had started it up,as soon as I start rollin the idle quicly raised up 2 normal temparature then about 10min more it'll overheat,so I had the water pump,timin belt replaced and got charged $290,how good of a deal is that ,thnx 2 a good buddy of mine's mechanic friend,really hooked it up,.....so I'm baring it down to prob being your water pump....GL bro

SmCross

I checked that after about 30 minutes of cool down after overheating.

I'm going to go ahead and just replace the radiator myself in a couple days as I found a good price on the part. Next stop will be the water pump!

Thanks for all the feedback so far.

SmCross

Update. Toying with the car trying to better pinpoint problem and figured out we have what I believe to be exhaust gas bubbles in the Rad overflow.

lionscourt

iTrader: (1)

keep in mind those radiator overflows' go bad too. They often develop cracks that lead to pressure loss in coolant system.

good2go

iTrader: (6)

How exactly does that work, considering that the overflow tank is not pressure sealed to begin with? You can leave the cap off of it and it will still work fine.

Rollin'ES3

If one of the hoses stays cold when the car is at normal temp. It means the thermostat isnt opening and closing properly. Its stuck closed. Just my 2 cents

SmCross

Despite having replaced the thermostat a couple months ago I took it out this morning and filled the car with water. (no coolant) and then drove about 15 minutes to work.

The temp gauge never went above the normal halfway point and now both hoses are equally hot. However when I shut the car down the water in the overflow was boiling vigourously.

99SC42

iTrader: (44)

It's either you have some air in the system or BHG.
Mine is boiling a last month and it ended up being the HG.

good2go

iTrader: (6)

My guess is that this is to be expected without the t-stat in place, since the water is no longer circulating and you are just using plain h2o the water left in the engine block will boil when you shut the engine off.

Sounds like you've just got a bad t-stat after all. Didn't you say you had tested and replaced it though? Did you mean: 'replaced with the original after testing it', or 'replaced with new after testing it' ??

SmCross

I had replaced with a New one at the beginning of the Summer. That is why I really didn't think it would be a bad tstat. In this case I would be delighted to be wrong.

Honestly the Tstat looked pretty rough when I pulled it out this morning.

I didn't have any coolant on hand so I'm gonna run and get some and see how things go.

LEXXIUM

iTrader: (1)

I'd definately try a different thermostat, before you replace wp. If that doesn't work proceed with wp replacement. The thermostats could be defective even if they are new, go with oem or trd one that runs a little cooler and it pops open earlier jmo.

SmCross

Well, I put some coolant in and drove about 15 minutes and I'm definitely overheating still... So I can't blame the tstat.