1989 XJS v12 coolant problems
#1
Guest
Posts: n/a
1989 XJS v12 coolant problems
hey guys, i currently own an 89 xjs v12, i have put a new water pump, thermostats, caps, and have flushed the system, and the car is still overheating, i have pressure tested the system and have tried gettin all the air out of the system and also have checked for exhaust gasses in the coolant and nothing, the car idles fine until it gets up too running temp then idle surges and causes massive over flow of the tank, as if it is air locking but i have tried everyway to get air out of it!! anybody got any ideas??? thanks
#2
Let me guess, it got worse after you had the radiator flushed. The folks that flush the radiator like to put in little gummy particles to prevent leaks. Unfortunately, your radiator may have been flushed several times before and is therefore partially blocked. With a conventional radiator, this only slightly lowers the cooling efficiency. The XJS V12 uses two inlets and devotes the top 1/3 of the radiator to the left engine bank. As the left bank water flows across the radiator the now cooler water must blend with the hotter water entering from the right bank. Normally this doesn't cause a problem when everything is new and working correctly. However, once the cooling performance drops, a over heating situation quickly develops. The hotter water from the right bank will develop a higher pressure than the left bank water which prevents circulation of the top 1/3 of the radiator. The left bank no longer has cooling and overheats.
The solution; rod your radiator, put in a new core or get a new one. I opted for an aluminum AJ6 radiator and modified the two inputs to only one. I had no problem with 104 F Florida heat. My cost: radiator - $250, piping - $100, labor - one weekend, experience - priceless.
The solution; rod your radiator, put in a new core or get a new one. I opted for an aluminum AJ6 radiator and modified the two inputs to only one. I had no problem with 104 F Florida heat. My cost: radiator - $250, piping - $100, labor - one weekend, experience - priceless.
#3
If there is air in the system it will cause the engine to run hotter. I had a radiator hose leak in the middle of the Australian outback a local friendly mechanic replaced with a modified Ford but did not bleed the system as per the book, as a result I had intermittent overheating.
The only way to flush the radiator is to remove the end tanks and brush clean it
The only way to flush the radiator is to remove the end tanks and brush clean it
#4
Join Date: Mar 2008
Location: Pacific Northwest USA
Posts: 24,927
Received 10,988 Likes
on
7,215 Posts
The radiator is a prime suspect, yes. And....it can be externally clogged with leaves and debris. You'll be shocked if you pull it out.
How's your fan clutch?
How have you bled the system? Did you elevate the front of the car and get a strong flow from the bleed hole?
Post back.
Cheers
DD
How's your fan clutch?
How have you bled the system? Did you elevate the front of the car and get a strong flow from the bleed hole?
Post back.
Cheers
DD
Thread
Thread Starter
Forum
Replies
Last Post
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)