Overheating? (1 Viewer)

[TLC58]

Hi,

First time poster from Austin. I have a blue April 76 FJ 40 (pretty much stock and still smogged) that I've owned for about 25 years, but I put it up for the last ten years. I've gotten it back out and am going through the mechanicals and electrical... lights, fuel lines/gas tank, brake system, new fluids, etc etc.

My issue is overheating. I pulled the radiator and had it cleaned out, put a new thermostat in, changed hoses and flushed the engine with water while I had the thermostat housing off. One new mod I did is to pull the rear heater pipes in the cab and put a by pass hose on the stubs entering the passenger side footwell beneath the dash (I had removed the rear heater years ago and decided I didn't need the tubes in the cab).

So, now the issue. The engine starts up fine and runs well, but after about ten minutes of driving (in 95 degree evenings) the temp gauge climbs past the last mark before "H". When I pull back into the garage at that point and shut the engine off it diesels for a couple of strokes and then quits. Then I hear a boiling noise from what appears to be inside the thermostat housing and upper radiator hose. Coolant is going into the overfill reservoir.

I pulled the thermostat this weekend and tested it on the stove in water and it opens at 180 degrees.

I'm wondering if its one of two things: (a) I have gunk in the front heater core/hoses or in the block or (b) my water pump isn't working.

I do have a new water temp sensor that I haven't installed yet. It would be funny/great if it showed a normal temperature range, but I don't recall the boiling noise and the dieseling before.

Any thoughts on what it could be and how to isolate the issue? How can you tell if a water pump is working? Fan runs fine.

Thanks!

 

[hooter]

4 thoughts

1) After a coolant exchange, it would be best to "burp" the system to insure no air is present. Air bubbles interfere with the systems ability to effectively cool.

2) check/replace your radiator cap to make sure no air is entering the system

3) check your timing. If way off, it'll contribute to the overheating problem and could explain the dieseling

4) check your fan clutch. fan could be spinning but not effectively


hOOter

 

[4x4veteran]

Dam Hooter you didn't give anyone else a chance.

 

[DylanZ]

I had the same issues, changed my cap and it was fine.

 

[Tools R Us]

Are both gaskets on the thermostat?

 

[Michael Hanson]

Hi, Park cruiser facing uphill and burp system. Also as above are both gaskets in thermostat ? Mike

 

[rrv333]

Cap change worked for me as well

 

[TLC58]

Thanks everyone!

So,
A. To "burp" the system, you park the truck uphill and start it up? Steepest hill you can find, or any uphill will work? Anything else? Radiator cap on or off?

B. I put a brand new OEM radiator cap on it, but I'll try putting the old one on.

C. Both gaskets are on the thermostat.

D. Looked at my fan, the Haynes and the Toyota repair manual. This is the first I've heard there is a clutch in the fan. I have the direct version, not the fluid coupler version. How do you check the fan clutch and where is it located?

E. I did notice the belt running around the fan and smog pump is slightly loose as well. I'll tighten that up. I assume you adjust tension on the belt by adjusting the smog pump on its bracket?

In the interest of science, I'll try each step separately!

Thanks again!

 

[skidplate]

AS long as your nose is pointed up you're ok. Open the heater valve, radiator cap off, run up to operating temp, top off coolant. If you have a clutch fan, you should be able to turn the fan by hand and feel a little resistance.

 

[hooter]

Get a lisle spill free funnel. it creates an airtight seal around the radiator cap and will allow air bubbles to vent from the system

https://www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY

any chance you were able to check the timing? that would affect the dieseling effect

hOOter

 

[hooter]

interesting, i thought fan clutch was for all years +75.....SOR has is from 8/76 and later. i guess you would be pre 8/76 on the build date which would explain no fan clutch. my bad.

 

[skidplate]

My July '75 has direct drive fan. No clutch.

 

[Michael Hanson]

HI, Any uphill,not real steep.Those radiator funnels are good to use ,you waste less radiator fluid. Turn heater(s) on. Mike

 

[TLC58]

Ok, I burped the truck tonight. Saw a few small bubbles and a couple of volcanoes of coolant. Temp gauge rose to the line before hot and stayed there. Topped with coolant. Shut it down, put radiator cap back on and started the engine. Went straight past the upper mark and stuck at H. Shut it down and heard a wailing sound I've never heard before. ..The radiator cap was venting!

Still wondering if the water pump isn't circulating water? What symptoms do you get when the pump goes bad? Would the fan still spin?

Hmmmmm......

 

[Solace in Solitude]

Burp it again.

The water pump has a weep hole below the pully... see if it’s weeping... weeping means it’s going down for the count.

Burp it again.

Repeat.

 

[Steamer]

Did you open the block drain? It's the low point of the cooling jacket and crud likes to settle there. How well it drains from there is kind of an indicator of the condition of the blocks coolant passages.

Flushing with a garden hose will only remove old antifreeze and debris that is loose and moves easily. If junk is stuck to the walls you may need some other flushing options.

Use the search function here for overheating, flush, flushing, block drain etc.

Oh, and welcome to the forum.

 

[brian]

Head gasket

 

[Gusb]

Just a comment that may help someone. Even though I've added coolant for years with the engine running, etc. done the same dumb thing twice now recently putting in new coolant. I do the 50-50 mix, fill up the reservoir and then fill the radiator to the top. Then start the engine and when coolant starts flying everywhere I run and put the cap on. That seems to effectively keep the coolant from circulating through the engine and everything begins to heat up. Stop the engine and go to remove the cap and the pressure is still there and sprays coolant everywhere. So maybe 1/2 a gallon or so in the radiator to start and just adding the balance (engine running) and everything would have been fine