So I’m new on here and I have been looking around at some different threads but can’t really seem to find much, so I figured I’d post my issue and see if anyone has any ideas. I’m not a mechanic and am not experienced at diagnosing problems. I can basically just do basic maintenance but I am trying to learn as I go.

I bought a 1988 pickup 4x4 22RE with 148k on it last week. Everything seemed to check out on it as far as my knowledge goes. I drove the truck home 200 miles, no issues at all. I realized when I got home the coolant level was a little bit low and the overflow reservoir was empty. I’m dumb and should have checked this before I drove that far. The truck has a new radiator on it, there’s green coolant in it, not sure how much that matters but it looks clean. I changed my oil this week and found that there was something blocking the drain plug, I’ve already posted about this and am going to check to see if the TC guides are broken with the valve cover off. My oil looks good, oil level was fine before I drove it home and it’s good now. I think there’s a small leak somewhere, maybe the front crank seal but I’m not so worried about that. I’ve been driving the truck just to work and back every day, only about 10-20 miles max a day and I have no issues. Yesterday when I was driving my temp just kept rising and luckily my work is only about 4 miles away and as I pulled in to park I was basically on the verge on overheating. I let it sit and when I left work opened the radiator and the coolant level was low but it looks like some of it had poured into the overflow. So I topped it off with distilled and got home safe. I let the truck run for a while once I was home and the temp never rose past half way. I smelled my radiator with the cap off and it smells like oil but there’s no sign of oil in the coolant, it looks clean as can be. My oil looks clean too. So what could be going on?? I don’t have loss of power, no white smoke, it does kind of smell rich though. I ordered a new oem T stat, maybe that was my issue? But I’m really hoping it’s nothing bad. Any help or advice is greatly appreciated.

 

A thermostat can't cause a low coolant condition. Not really. An overheat, yes.
If they replaced the radiator, a new T-stat, especially a 2-stage one, is a very good, inexpensive, idea. Fairly easy to get to, as well. 2 bolts, right out in the open, up top. Follow the top radiator hose, and pull off the piece it connects to, called the thermostat housing. A new o-ring for the thermostat is a real good idea, as well. I've found that a really thin layer of Vaseline on o-rings helps them seal better, and last longer.
Make sure when you install the new t-stat, that it's oriented correctly. The small opening should be at the back, IE: facing the fire-wall. Even a single-stage thermostat will work, although a 2 stage is the preferred version. Make sure the little "jiggler" valve in it is, again, twords the firewall.
You don't have to empty the radiator and system completely. Just a half gallon or so, until the level is below the thermostat.

Make sure the hose running from the radiator to the recovery tank is connected to right connection. It should go the one that goes straight down inside the recovery tank, from the cap, which should have a hose on it that just reaches the bottom of the recovery tank. The other pipe, that should have a hose on it that feeds over the side of the tank, on the outside. That pipe is for recovery tank overflow, which you shouldn't need to worry about. It also lets any air that bubbles out of the radiator blow overboard, so that when the system cools, it draws fluid in from the long hose IN the recovery tank to replace the air. Cut the hose inside the recovery tank at an angle on the end that goes to the bottom. That keeps it from sealing down onto the bottom of the recovery tank, preventing the radiator from drawing water in.

Again, once you have the system closed back up, and refilled, make sure you burp it. You won't be able to put as much coolant back in as you took out. You will eventually, don't worry. If you have a hill you can park on, park nose-high on it, make sure the radiator is full, make sure the heater valve is opened fully, and let the engine warm up all the way, with the radiator filler cap off, or at least loose. You can also run the front wheels up onto work ramps, or jack it up and put jack stands under it, if you don't have access to a hill. Triple check the transmission and transfer case are in neutral!! Block the back wheels as an additional safety measure.
Beware, it will overflow some as it warms up, but it will stop once it levels out temperature wise. I just leave the radiator filler cap on, but not tightened all the way. Only the first part of it's clamping down. That will direct the small amount of overflow to the recovery tank. Once the thermostat opens, you can pull the cap off, and make sure the flow is good in the radiator, thus verifying the pump's operation. Then, top the radiator off, and cap it all the way tight.
Once the truck is real good n warm, I let mine run 20-30 minutes, close the radiator cap all the way down tight. Make sure there's the right amount of fluid in the recovery tank. Maybe a little bit too much, as it's likely the radiator will draw fluid out of the recovery tank.
Once it's cooled down all the way, check the level in the recovery tank, and the radiator. Top as required. As you drive it, it may well draw some more fluid from the recovery tank. Just keep it at the "FULL" line if it does.

Quite often, what you experienced is from an air bubble trapped someplace in the system, which comes free and runs to the radiator, thus overfilling the recovery tank. It then, as it cools, draws the fluid out of the recovery tank. A big bubble can drain the recovery tank, and allow air back into the radiator, once it's completely empty.

When the radiator was replaced, are you sure they burped it completely? Did they replace the three big radiator hoses? Do the small hoses that feed the intake manifold and throttle body look good? No leaks, cracks, etc?
Any leaks from the heater core in the cab? If you have one, any leaks from the back seat heater core?

Does your fan clutch engage properly, when the truck get's good-n-warm? Remember, the temp gauges in these are notoriously unreliable, as to accuracy. Try getting a thermometer you can aim at different places from a distance, and use that to read the temp on the thermostat housing with the thermostat open, and the coolant flowing normally. Make sure the gauge matches. It should read 185-190° F, when the gauge is about a half, or so.
If the fan clutch doesn't engage, replace it immediately.
Is the radiator shroud in place, including the little piece at the bottom? If not, put it in place immediately, or buy a new one. It's an important part of the cooling system.

I hope something in all my rambling helps a little bit...
Pat☺

 

Thanks, Pat.

This is all really good information and helped me understand what my issues may be. I have not had any issues since i have topped off the radiator, cleaned out my overflow reservoir and topped that off as well. Although, I did find a dead rat in my overfllow reservoir, this truck did come from a ranch but I have no idea how the rat could have gotten in there before. I've got my thermostat coming in the mail this week (just got a single stage oem one from 22RE Performance), once it arrives I'll replace it and follow what you've told me. No leaks in the cab, no idea if the PO burped the new radiator. I will get all of that taken care of.

 

1) EWWWwwww!!
2) If that thing was lodged somewhere in the coolant system, in a hose, or something like that, it may have broken loose and somehow, I have no idea how at all, gone into the recovery tank. I doubt it, as the hoses feeding the recovery tank are pretty small.
I would check over the recovery tank for a hole the rat may have chewed in it to get in. Much more likely. The tank is easy to pull off. Pop the top, two bolts right there where it's mounted, and that's it. Don't even have to empty it. Just look it over real good, especially in the less obvious areas. That rat got in somehow! They can get in through some pretty small holes, believe me!
When I was a kid, 14, or 15, I used to raise rats for pets and snake food. They can really squeeze down small.

Doesn't sound like he did, but only he knows
Did you check for leaks with the heater valve full open? IE The temperature control on the control panel all the way to hot? You need to be sure you've got flow into the heater core, or leak(s) may not show up, if they exist. The thermostat doesn't even need to be popped. It gets full flow from the pump whether the thermostat is open or not. With the valve open! In other words, it's up-stream of the thermostat.

That's one reason they came up with the 2-stage thermostat. The "cold" return water from the cab heater(s) feeds back in right before the thermostat, and can tend to hold the thermostat closed longer than would be the case without the cab heater(s). Thus, the engine temperature can rise higher than expected before the thermostat opens. With the 2-stage t-sat, the smaller valve opens at a lower temp that the big one, allowing SOME flow through the radiator, preventing, or reducing, the high temp condition.
A little trick you can use, with a single stage in, is when the temp goes above about a halfway point on the gauge with the heat in the cab on, close it for a few minutes. That will stop the "cold" water from flowing onto the thermostat, allowing it to open properly. Once the temp comes back down below about a half on the gauge, turn the cab heat back to where you want it. The thermostat may "hunt" for a while, with the temp gauge going up and down in a decreasing pattern, as the t-stat finds the new balance point. It will settle pretty quickly, though.

Good luck! Keep us informed on how things go
Pat☺