'99 SR5 here... 245k on the clock. Swapped out the auto trans solenoids the other week and now the truck is overheating. I find it strange that right after I swap these it starts to overheat when it never has before. The plan, since it is new to me, is that I'm going to end up swapping the thermostat, water pump, timing belt, serpentine belts, radiator and both hoses. I think the clutch fan is fine, but while I'm doing this, I'm debating on a separate trans cooler too and maybe an electric fan. Any ideas on what is causing the overheating or the work I'm about to do in a week? Thanks in advance.
Overheating issue
- Thread starter ccurrans
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When is it overheating? Just sitting, moving at low speed, highway speed, under load? Are you watching the gauge in the dash or do you have something to see the exact temperature? How quickly is it overheating?
I haven't checked with it just sitting yet, but not under load and was at highway speed around 60 and was watching the stock temp gauge. I'll check tonight and see if it overheats while at idle. I did notice that at one point, I let off the throttle and the temp went down, so take that for it's worth as well. Thanks for the help.
brillo_76
Elite Member
1.) make sure the radiator is full of clean antifreeze
2) when you see the gauge creeping up. Turn your heater on full blast and see if the gauge returns back down. If it does, then most likely your thermostat is just sticking closed.
Was very common on the older 80's pickups and now that these are all mostly close to 20 years old, its possible that yours was never changed or just going bad.
Lots of writeups and videos out there how to change the 3rd gen thermostat. If that is indeed the cause of heat-up.
Also, lots of people bypass or put in series an After Market transmission cooler. Many threads on this forum as well on how to do that.
I myself, do not put A/M coolers on. I just replace the radiator every 10 years with a new Denso one (around 100 on rock auto) If majorly hauling might be a good idea to put one in series with the radiator. However, Liquid to liquid heat transfer is far more efficient then air cooling. { That is just me though} Lots of people don't want to take the risk and bypass the radiator cooler. So whatever you wish to do is good.
phattyduck
Elite Member
The thermostat alone is very easy. Even the rest is fairly straightforward. The only 'gotcha' is putting the thermostat jiggle valve down instead of up like it is on basically every other engine.
Hopefully it isn't a head gasket issue. Check the easy stuff first (full of coolant, etc.) and go from there.
-Charlie
mtbtim
Elite Member
These videos might help you out:
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<iframe width="560" height="315" src="https://www.youtube.com/embed/WzhlACxqeqQ" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
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Had an older Camry years ago that suddenly started overheating at highway speeds. Would cool down and indicate normal at idle and slower speeds. After replacing the thermostat and flushing the radiator made no difference someone suggested the radiator hoses. They postulated that at high speeds the weak older lower radiator hose was collapsing due to the higher suction pressure. A new hose solved the issue.
phattyduck
Elite Member
Along those lines, a slightly leaking radiator cap can do the same thing. Go OEM on the radiator cap, it is the only one that is guaranteed to work...
-Charlie
brillo_76
Elite Member
The pressured system should keep the rad lines from trying to fold in. Very good thought on the Radiator cap Charlie as that would cause issues. Especially if the rad was changed and still has the oem original cap with a bad defective seal on or some A/M junk one.
gamefreakgc
Elite Member
Don't go e-fan unless you have a reason to, this is coming from an e-fan user. It makes the system more complicated. Mechanical fan will always work, even if the clutch seizes it will still work great just always be on lol.
Were you planning on doing the timing belt anyway or are you doing the timing belt because you figured on changing the water pump, which you figured on changing because of the overheating issue? If you are, start with just the radiator and hoses and see if that's all it was. Changing out a radiator is waaaay easier than an entire timing belt change.
brillo_76
Elite Member
I agree with gamefreakgc. Stick with the standard original fan which is 80's tech that is dead on reliable.
I haven't seen a OEM toyota water pump fail that didn't leak on any Toyota cause a heat issues. Mostly when the bearings fail and they start spitting antifreeze when the heat issues start with then.
I have seen stuck thermostats, stop leak filled engine water jackets, plugged or debris clogged radiators both externally and internally and non pressurized cooling systems have heat issues.
So if your not loosing any coolant on the ground and its not in your engine oil, when you start up the engine does it have lots of white smoke?? If so, the coolant could be leaking into the cylinders from a bad or leaking heat gasket. However, you would see this in coolant level dropping too.
BoomerBob
New member
If you don't already have an Ultra-Gauge MX- with trans temp built in for 99 and newer T4R's; I highly recommend them. Spiker Engineering, a member here, has a great mount for it too.
UltraGauge, OBD II Scan Tool & Information Center
Ultragauge Mount - Spiker Engineering
Thread with more info and putting the right code in for the trans temp reader.
https://www.toyota-4runner.org/3rd-...stion-trans-temp.html?highlight=UltraGauge+MX
For under $130 total you can set alarms to sound and alert you to an overheating condition before it does damage to your engine and/or transmission. Very inexpensive permanent insurance you can move to another vehicle if you end up selling the current one.
This won't help you fix your current issue but it will help you or anyone prevent a major engine failure. I'm also one of those who bypassed the radiator with an external trans cooler so I never have to worry about the dreaded pink milkshake.
I'm so impressed with these little multi-gauges that I bought one for my 99 Mustang GT so I can monitor temps and get alarms for it too. The added 140 or so possible sensor readings are icing on the cake. I use the MPH, MPG average, and MPG instant quite a bit too.
Sorry for the delay in responding, lots of people leaving at work, so we are a little thin.
Not seeing any white smoke on start up. What it turned out to be was little to no antifreeze. Bought this from a guy who said it just had the head gaskets replaced. Not sure I buy that now.
No puddling anywhere of any kind. I refilled the radiator and havent overheated since. Still no puddles.
She has 250k on her and dont know if the timing belt has ever been changed so figured why not and do the water pump, thermostat, etc... still havent done this yet, mind you.
Figured I would throw more wet spaghetti at you guys and see what you think. Thanks again for the input.
brillo_76
Elite Member
To check the belt. Look for micro-cracks. If they are close to 20 years old you can tell by looking at the belt. You can just pop the top plastic cover off to look at the belt. Mind you will also have to pull the top radiator hose as well to take that plastic cover off. My 97 5 speed had not only the original timing belt but the original belts too. When I brought it home.
Glad to hear it was something simple like no antifreeze and thanks for letting us know.
I'd do a compression and leak down test of the cylinders before doing the timing belt/water pump. That should be able to tell you if you need to replace the head gaskets which would require removing the timing belt to do.
Well, took her out for a drive today. About 2-3 miles in, had to stop at UPS. Came out of the store and noticed something dripping on the passenger side... antifreeze. A good amount too for as little as I drove. Maybe 6 ounces? Anyway. Drove straight back home and took a look underneath and saw where it was dripping off the frame rail where the cross member is. Looked along the frame rail on the passenger side and see where there are 2 lines pretty rusty. Any clue on what these are? Also, the antifreeze was not a gravity drip from the top of these 2 lines from the engine bay area, but more where it runs along with the frame rail horizontally which coincides with where the rust is on these lines. They dont appear to be rusted through, but could be wrong. In short... HALP!!!! Lol. Thanks again guys.
If you kept the old solenoids might want to put them back in. Were they OEM?
Was tranny giving you issues?
Did you change all the fluid? 5 quarts?
Is the level right?
Put it on a Code reader and see what you find?
mtbtim
Elite Member
Well, fan clutches don't just fail one way. They can like you said stay locked up and lower your fuel efficiency but they can also fail to lock up when your engine reaches the magic temperature. The fan looks like it's spinning effectively but it really isn't. When the fan clutch fully locks up, it should be turning at the same rpms as the engine. When it's not locked or not fully locked, it's turning slower than the engine.
A bad fan clutch failing to lock up like it's suppose to has quite often been the culprit of why an engine overheats especially when the vehicle is stopped or not moving fast. When the vehicle is moving at a decent speed, air is being forced through the cooling fins of the radiator and the effectiveness of this cooling is directly related to the ambient air temperature. Basically, your engine is going to run hotter in 100 degree temps as compared to 70 degree temps. When you come to a stop, you no longer have air being forced through the cooling fins of the radiator. The only thing helping with the cooling at a stop or at a crawling speed is the fan clutch pulling air through the cooling fins. If the fan clutch isn't locking up like it's suppose to, the engine will overheat.
Here's a couple videos that explain very well how a fan clutch works:
YouTube
YouTube