YFZsandrider

Truck- 1993 extracab SR5 3.0

I ran a search, but couldn't find anything that matches my unusual cooling problem.

I bought the truck about two months ago, and noticed that the temp guage would read hot, only a little below the red on longer drives... so I replaced it with an Autozone thermostat(ya, ya I know... didn't have any money at the time), and the overeheating issue cleared up. Or it seemed to anyway.

Now, after replacing the thermostat, the truck runs at a temp that seems a little low, if anything. The needle reaches a little higher than the beginning part of the temp range, and it will occasionally get closer to the halfway mark, but usually is down at less than 1/4 on the guage. Now, this is how it usually runs, unless I let the truck idle for a while, without driving it.

Case in point... yesterday, I had been out driving for about an hour, when I got a phone call, I pulled over and talked for about 5 min. I noticed that my temp guage had reached pretty close to the red, but when it gets that high, my heater blows out cool air! If I begin driving, or give it gas, to bring the idle up to around 1500, the heater will blow out hot air almost immediately and the temp guage will drop back down.

All of this is happening in 40-70 degree weather. It seems to me like there must be something wrong with my water pump, kinda like its not moving a volume of water unless I'm driving or the idle is held up a little... any ideas on this problem??

YFZsandrider

anyone have any ideas?

bump!

vital22re

iTrader: (2)

air in the system? hows your coolant level? Have you ohmed out your coolant temp sender?

Brando338

Does the aftermarket thermostat have a breather valve near the top of it cuz I ran one from Napa and it didnt have a breather like the oem one does so my truck was overheating.
Also, the previous owner installed the headgaskets on backwards or something on mine I guess its pretty common and easy to do if you dont pay attention(morons) so my truck runs an open flow thermostat. 3.0

phildelfino

Those are the symptoms for low coolant level and/or air in the system. Climb the front end onto something, when its warmed upped, so the radiator cap is higher than anything else in the system and remove the cap. It should take a couple quarts of coolant.

muddpigg

iTrader: (1)

Symptom of air in the system as mentioned, or one of the thousand ways a blown headgasket will present. That is what mine was doing; wouldn't have believe that it was the headgasket till I smell exhaust and raw fuel coming out of the radiator on one of the several times I tried to bleed the air out.

phildelfino

^^^ Good call.

McKenna

Since you just purchased the rig, you may want to look into flushing your cooling system with new coolant if your mix of Distilled water & Antifreeze additives are not up to snuff (If you hadn't already done that). Then purging the air from your system would occur when you flush with new coolant. Make sure you check to see if your drive belt is properly adjusted so the Water pump keeps spinning. I'd also swap your Radiator cap, its cheap insurance and they are the most overlooked part when it comes to your Temps rising.

YFZsandrider

Thanks for all the responses so far...

Just to adress a couple things, the truck has a new readiator in it, within the last year. When I went to look at the truck, before purchasing it, the radiator level was about 3 or 4 quarts low. It didn't seem like the previous owner propaerly bled the system. After topping the level off, all was good.

I changed the thermostat out for a OE temp unit, which does have the small breather at the top.

All the coolant looks extremely fresh! It was mentioned that a blown head gasket can show itself through exhaust and raw fuel entering the readiator... what would be a good way to check for this??

I have not checked the coolant temp sender for proper function, although I would say that it is working properly, as the heater peformance and the coolant temp are directly related when I am experiencing this issue.

Thanks for the responses, guys!

YFZsandrider

actually, after seeing this, I went out and checked it... looks like it was about 3 or 4 quats low in the radiator... so I topped it off, though it still had a little more than half full in the overflow reservoir... why is that?

Also, we've been having unusually cold temperatures this week, its been about 20 degrees F overnight. I'm not so sure that the missing fluid was a large air pocket that surfaced, though... I think I'm slowly eating coolant somehow? Does that make sense??