Help Needed - Overheating on Startup after Desmog (1 Viewer)

[fwsmittyk]

Completed desmog taking great care following desmog threads on this site. Started right up sounded great but began immediately overheating and didn’t seem to be pulling coolant into block since I was trying to add coolant needed from some loss after pulling lower valve off thermostat. Thought maybe overtightened belt on the new pulley and damaged bearings in water pump so replaced pump and coolant temp sensor. Apparently wasted all that time and money because just started her up and immediately overheated. Again it doesn’t seem to be pulling coolant from radiator at all since again I was trying to burp radiator after filling to complete water pump project. I guess question is what vacuum line(s) misplaced could cause immediate and rapid overheating? Any suggestions appreciated.

 

[g-man]

3FE?? Describe immediate and rapid overheating? How did you determine the engine temp? Did the temp gauge go all the way up to near the red? Did you put a heat gun on the head? Not much in the way of desmog stuff that is going to make you overheat.

The water pump could be working but until the thermostat opens up ...no coolant is going to move. When the t-stat opens the radiator top hose should go from tight and warm to spongy and HOT immediately and you should see you temp gauge drop.

Not sure what the "lower" valve is on a t-stat. Do you mean you pulled the bottom 1/2 of the housing? When I replaced the cylinder head on my 2f I removed the lower t-stat housing and all the coolant out of the head. When I restarted it I just let the water pump push it back in there. Of course you will have to burp it. some jack up the front of the vehicle. I just let it go thru a couple of heat cycles until the t stat opens. In other words I let it warm up until I see the temp gauge go a little past 1/2 then cut it off. Then do it again a few times like this until the t-stat opens. I never let it get near the red line.

My experience with failed water pumps is that they will weep from the hole at the bottom. Do you see coolant puddling or dripping from the bottom of the water pump?

 

[OSS]

There's an air bubble trapped in the cooling system is my guess

 

[fwsmittyk]

Thanks for responding G-man. Sorry thought I posted in fj60 forum. So it’s a stock 60 with 124k original miles. On 2F there are 2 bvsv valves in lower thermostat housing and the lower valve is removed in desmog which causes coolant to spill until plugged. The upper valve has nipple for 2 vac lines that are rerouted for the desmog. No idea what the valve does or if it has anything to do with the thermostat operating correctly but I doubt it because I think some people remove both of them. Anyway, when it starts up I watch engine temp gauge and it moves to top of temp within a few minutes - basically as engine reaches operating temp. I don’t know why the thermostat would have suddenly malfunctioned after desmog - it has only 3,000 miles since replaced it new.

 

[fwsmittyk]

OSS, thanks but wouldn’t an air bubble clear after running for several minutes. Truck was jacked in front, I tightened hoses down, filled radiator, turned heat on high and one thing I was surprised about is I left radiator cap off to burp and both times the coolant almost immediately poured out of radiator cap instead of being sucked down like I expected.

 

[Seth S]

OSS, thanks but wouldn’t an air bubble clear after running for several minutes. Truck was jacked in front, I tightened hoses down, filled radiator, turned heat on high and one thing I was surprised about is I left radiator cap off to burp and both times the coolant almost immediately poured out of radiator cap instead of being sucked down like I expected.

Unfortunately no. On these trucks air bubbles are a real challenge. It can take a while to get all the air out of the system after draining and refilling the coolant.
also you did post in the 60 series area of the forum but it’s good habit to state whether you are talking 60 or 62 as they do have difference that can affect the path of recommendations and diagnosis.

 

[Seth S]

concerning the Bsbv valves in the T stat housing....you can leave them in there when you desmog and just disconnect the vacuum lines. If the valve is leaking then it’s a good time to pull and plug the hole. If not it makes a good enough plug. One Bsbv valve is for the EGR system and the other one I can’t remember.

 

[Seth S]

if the truck was fine before the desmog and it overheats after air is the most likely culprit. There just isn’t anything you do in the desmog that would cause an overheat. Unless you were just very unlucky and the stars aligned and your thermostat decided right then to stick closed. Etc

 

[fwsmittyk]

Thanks all, so... what is the trick in getting the air bubble out? Honestly the engine was literally smoking and temp gauge To top red within 2 minutes so I can’t attempt to get the bubble out while engine is running or it will melt down. I didn’t drain the block of coolant so should I go through trouble of draining the entire system and go from there?

 

[BlackCat]

The truck cannot physically overheat in 2 minutes. It’s impossible. A large enough air pocket will give false hot readings on the stock gauge as well.

 

[FJACS]

Got the thermostat in upside down?

 

[fwsmittyk]

The truck cannot physically overheat in 2 minutes. It’s impossible. A large enough air pocket will give false hot readings on the stock gauge as well.

Thanks BlackCat I didn’t know that was impossible. Don’t understand why smoke rises from engine - maybe just penetrating oil burning off but it’s taking a long time to burn off. I’ll just keep running it and try to burp it out.

 

[fwsmittyk]

Got the thermostat in upside down?

No but appreciate the thought and I’ve heard about folks doing that! I did not remove thermostat for either the Desmog or the pump job.

 

[4runner2FJ60]

You might want to pull the sender real quick and see if you can see coolant in there.....engine off of course.

 

[MoaByte]

Using a tight fitting funnel helps. I took mine for a slow crawl on steep slickrock. Afterwards, topped it off. That 90° angle on the filler is a PITA.

 

[fwsmittyk]

Using a tight fitting funnel helps. I took mine for a slow crawl on steep slickrock. Afterwards, topped it off. That 90° angle on the filler is a PITA.

Thanks yeah I have regular funnel I press down on while filling but nothing is moving after the initial fill - just pours back out within seconds after start. Done this at least 3 other times and never a problem - fast burp, run and top off in just a few minutes. Something is f@&d up with it.

 

[fwsmittyk]

You might want to pull the sender real quick and see if you can see coolant in there.....engine off of course.

Sender? You mean coolant sensor? I assume if don’t see coolant it’s not pumping through block. So what would that tell me?

 

[4runner2FJ60]

Yes temp sender. There are a few entire threads on the air bubble at the temp sender issue that causes the sender to not function correctly. If coolant is not up to the that level there is burping left to be done.

 

[MoaByte]

It's been awhile, but I remember using the overflow reservoir for the final top off because of the upchucking. I pumped the upper hose.

 

[WILLD420]

I always drill a small 1/16 inch hole in thermostats to burp the air out without getting them up to temp. Parking with the nose uphill helps a lot. Just don't poke too big of a hole in there. You can cause problems that way.