Overheating...

Joined
Nov 27, 2004
Messages
82
Location
Cambridge, UK
my 1KZT engine has begun to overheat. This is a new thing for it. My engine doesn't smoke. It's not leaking oil. My coolant reservoir is full but the radiator continually looks dry [so i keep topping it up].

any ideas on what to look out for would be appreciated.

the engine is bog std. and has done 125,000 miles and up until recently has run absolutely faultlessly. The first time we std to notice it overheating was in low gear up an extremely steep bank. But, we've also noticed the guage fluctuate hugely for no reason at all when driving on the flat?

thanks all for your help

Al
 
Joined
Nov 27, 2004
Messages
82
Location
Cambridge, UK
thanks for your responses... i understand about testing the pressure in each cylinder but how/where does one test coolant pressure and how/where does one test for combustable gasses in the coolant?
 
Joined
Nov 27, 2004
Messages
82
Location
Cambridge, UK
oh... if it helps.... I've seen it before that the coolant is getting lost as it's running out the overflow pipe. Would this indicate that there is too much pressure in the coolant?

Also whould would too much pressure in the coolant or combustable gasses in the coolant indicate?

Sorry for 20 questions but it does concern me and i want to sound somewhat knowledgable when i go to a garage rather than paying £60 for unnecessary research as they fumble around.
 
Joined
Apr 4, 2004
Messages
616
PJHunter said:
oh... if it helps.... I've seen it before that the coolant is getting lost as it's running out the overflow pipe. Would this indicate that there is too much pressure in the coolant?

Also whould would too much pressure in the coolant or combustable gasses in the coolant indicate?

Sorry for 20 questions but it does concern me and i want to sound somewhat knowledgable when i go to a garage rather than paying £60 for unnecessary research as they fumble around.
Could be building pressure from a headgasket or cracked head, but I would check the rad cap first it might have failed and letting out coolant early, a pressure test on the cooling system will tell if it something serious or not.
 

Stone

Moderator
 
Joined
May 13, 2004
Messages
3,130
Location
BC, Canada
PJHunter said:
/where does one test coolant pressure and how/?

You can buy a cooling system pressure tester in most parts stores. It looks like a radiator cap with an attached rubber hose and bulb, similar to the ones they use in hospitals/doctors' offices to test your blood pressure. You take off your rad cap, replace it with the pressure tester cap, pump up/pressurize the system, and sit back and watch for leaks or for the pressure to drop. If your system is good, then it should hold the pressure. Good luck.

Or this is a fancier one:


http://www.northerntool.com/webapp/wcs/stores/servlet/NTELargeImageView?rfno=200215424&storeId=6970
 

crushers

post ho
 
 
Joined
Feb 10, 2004
Messages
22,188
Location
Tara Ontario
mallred said:
Could be building pressure from a headgasket or cracked head, but I would check the rad cap first it might have failed and letting out coolant early, a pressure test on the cooling system will tell if it something serious or not.
agreed, start cheap and work up...
 
Joined
Nov 27, 2004
Messages
82
Location
Cambridge, UK
i am finding this all very helpful. So thank you. I will go and look at buying a pressure testing kit today...

...just out of interest what would your thoughts be if the pressure test was actually ok? Would that mean it would definitely be something more serious like a cracked head or head gasket??
 

crushers

post ho
 
 
Joined
Feb 10, 2004
Messages
22,188
Location
Tara Ontario
if there is no leak occuring outside the block or into the passenger compartment (ie the heater core leaking) then yes it has to be loosing the pressure inside the block somewhere..
 

David*BJ70

Looking forward to reach the end of the world
 
 
Joined
Jan 13, 2004
Messages
1,755
Location
Montréal, Canada
Before, I have the same issu.

No coolant in the oil, non smoke, everything look dry... but after severale minute at high speed, all the coolant get out by the overflow pipe.

I first change : water pump, radiator, some hose, T-stat, some gasket ant the rad cap.

I try compression test.. but that not give me the answer.

My solution : new head gasket. The piston pressure seem to get out in the cooling system.

HTH
 
Joined
Nov 27, 2004
Messages
82
Location
Cambridge, UK
wesintl said:
On the cracked heads I've had I've found the pressure test to be worthless.
So you're saying the pressure test didn't achieve anything?

also... is it likely that a head would 'just go'? Wouldn't it take some extreme lack of maintenence or neglect to stuff a head?

And wouldn't a head gasket 'just go' as well? Or are there cases where just through sheer time and age a HG would just wear out like any other component?? Also I always thought that where a HG had failed the engine wouldn't maintain any form of stable temp at all. Is my thinking wrong?

On another note... when to buy a pressure test kit today but Halfords didn't have any. So I'll have to find another local automotive store here in Bristol that stocks 'em.
 

wesintl

 
 
Joined
Mar 14, 2003
Messages
4,523
Location
Between Here and There
PJHunter said:
So you're saying the pressure test didn't achieve anything?
Yep pressure was fine. I left it on there for a bit too and it held steady. That was on my fj60.

Exhaust gas in the cooland test is the best option IMHO.
 

crushers

post ho
 
 
Joined
Feb 10, 2004
Messages
22,188
Location
Tara Ontario
wesintl said:
On the cracked heads I've had I've found the pressure test to be worthless.
did you do a cold test or a hot test? i have had good results doing this test...
cheers
 

wesintl

 
 
Joined
Mar 14, 2003
Messages
4,523
Location
Between Here and There
crushers said:
did you do a cold test or a hot test? i have had good results doing this test...
cheers
Yep. I think a cold one is worthless. It's gotta be hot for the crack to open up hoses get soft for pin holes etc.. FWIW we did it at a mechanics shop to so unless we were both seeing things It didn't work. Actually I should modify my statment as I didn't do it on the 3B. I only did the gas pressure test and I pretty much knew from driving and loss of coolant what the problem was. It doesn't take a rocket scientist to know what's going on although at the time I was trying hard not to believe it. :frown:

JMH.02
 
Last edited:

wesintl

 
 
Joined
Mar 14, 2003
Messages
4,523
Location
Between Here and There
PJHunter said:
but what would cause a head to crack if it hadn't overheated before?
stock gauges aren't always accurate. Not saying it is a head crack but your coolant is going some where, either through a crack or bad gasket. Pressure test at least can help with pin holes in hoses and bad connections where you loose coolant onto the engine and it burns off. :)
 

crushers

post ho
 
 
Joined
Feb 10, 2004
Messages
22,188
Location
Tara Ontario
wesintl said:
Yep. I think a cold one is worthless. It's gotta be hot for the crack to open up hoses get soft for pin holes etc.. FWIW we did it at a mechanics shop to so unless we were both seeing things It did work. Actually I should modify my statment as I didn't do it on the 3B. I only did the gas pressure test and I pretty much knew from driving and loss of coolant what the problem was. It doesn't take a rocket scientist to know what's going on although at the time I was trying hard not to believe it. :frown:

JMH.02
yes, i have found a cold test is worthless but a hot test does help. i have never done a exhaust gas test, how is that done?
 
Top Bottom