1hz Overheating

Joined
May 26, 2020
Messages
36
Location
Iran
Hi everyone
It has been 2 years of running a 12v 1hz on my FJ45. Everything is OK until the summer comes and overheating problem begins.
I have checked all components of the cooling system.
The injection pump seems to work normally because no smoke comes out of the exhaust.(Just a little black smook sometimes.)
Overheating just happen when I'm driving in 35°C or above and at 80-90km/h with the 4th gear.
Something I should add is that I have removed the clutch fan and the fan works without clutch.
Any idea?
 

Squash

SILVER Star
Joined
Dec 8, 2006
Messages
1,694
Location
Sudbury, Ont. CA
Have you updated the rad?
My HZJ75 would start to warm up if I was traveling over 90km/h
I finally broke down and re-cored the rad. Now that worry is over. The re-core was not cheap and if I had to do it again I would custom fit a modern HZJ79 rad. In my case it would have been relocation of supports, and lower hose adapter.
 
Joined
Dec 6, 2021
Messages
70
Location
Israel
Have you updated the rad?
My HZJ75 would start to warm up if I was traveling over 90km/h
I finally broke down and re-cored the rad. Now that worry is over. The re-core was not cheap and if I had to do it again I would custom fit a modern HZJ79 rad. In my case it would have been relocation of supports, and lower hose adapter.
@Squash , would a new style HZJ79 fit the narrow older 1990's style engine bay, front grill support and lower crossmember design and position?
If so, and only minor fab work needed, than it sounds like a very comfortable solution.
Would you prefer the plastic manifolds over the older metal ones?
 

Squash

SILVER Star
Joined
Dec 8, 2006
Messages
1,694
Location
Sudbury, Ont. CA
@Squash , would a new style HZJ79 fit the narrow older 1990's style engine bay, front grill support and lower crossmember design and position?
If so, and only minor fab work needed, than it sounds like a very comfortable solution.
Would you prefer the plastic manifolds over the older metal ones?
I was was loaned a 79 rad and feel it would fit if you removed the supports and used your old rad's support hardware. Best to compare both together.
The other thing to consider is the bottom hose as the fittings on the brass vs plastic rad are different.
 
Joined
Dec 6, 2021
Messages
70
Location
Israel
I was was loaned a 79 rad and feel it would fit if you removed the supports and used your old rad's support hardware. Best to compare both together.
The other thing to consider is the bottom hose as the fittings on the brass vs plastic rad are different.
Thank you for the valuable info
I might have an option on some 79 parts
Also good to know that some longevity on much needed parts is out there
 
Joined
May 26, 2020
Messages
36
Location
Iran
Have you updated the rad?
My HZJ75 would start to warm up if I was traveling over 90km/h
I finally broke down and re-cored the rad. Now that worry is over. The re-core was not cheap and if I had to do it again I would custom fit a modern HZJ79 rad. In my case it would have been relocation of supports, and lower hose adapter.
Actually my radiator is really a big one and I have relocated it before.No changes at all.
 
Joined
May 26, 2020
Messages
36
Location
Iran
Maybe test for cracked head
20220701_224545.jpg

There was a creck there and I covered it by cylinder glue. Small amount of oil used to coming out of there.
But what is the relation?
 

GTSSportCoupe

2LTE abuser
Joined
Mar 23, 2012
Messages
8,370
Location
Victoria, BC, Canada
View attachment 3047490
There was a creck there and I covered it by cylinder glue. Small amount of oil used to coming out of there.
But what is the relation?
The cracks would be between combustion chamber and coolant passages. Cylinder head needs removal to see.
 

Users who are viewing this thread

Top Bottom