Radiator bleed problem
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Junior Member
Joined: Jun 2016
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From: Michigan
Radiator bleed problem
Hey guys I’ve been a member for a while but never posted before. Thanks in advance for your help. I’m trying to bleed the radiator on a 1990 Xjs v-12. I’m trying to follow the often posted directions but when I try to run the motor with the filler caps off, it just gushes coolant from both filler pipes. What am I doing wrong?!
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Joined: Mar 2008
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From: Pacific Northwest USA
Hey guys I’ve been a member for a while but never posted before. Thanks in advance for your help. I’m trying to bleed the radiator on a 1990 Xjs v-12. I’m trying to follow the often posted directions but when I try to run the motor with the filler caps off, it just gushes coolant from both filler pipes. What am I doing wrong?!
Hate to say it but my first thought is a blown head gasket allowing compression to be pumped right into the cooling system. Hope I'm wrong. As already asked, what's the history here? Other work done?
Cheers
DD
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From: France
I would not run the engine with both filler caps off, I think you may have misunderstood the procedure. Try this in this order:
- First remove both caps
- Second fill the wing tank until it is full and replace the cap
- Third fill the centre spout until it is full
- Fourth, start the engine, heater on DEFROST and run it for 3 minutes
- Fifth, remove the centre spout cap and top up, replace cap
- Sixth, remove the small bleed screw-in bung from the top LHS (US driver's side) of the radiator. Keep a jug of coolant ready
- Start engine and top up the system through the bleed hole until it seems full and overflowing.
- Replace bleed screw
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Junior Member
Joined: Jun 2016
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From: Michigan
Thanks guys! Here’s a brief history. Car has 80,000 on the clock. I’ve owned the car for 2 years. It blew a head gasket last fall. I had a used motor installed at a well reputed shop here in SE Michigan. Motor has 50,000 on it and was given a clean bill of health after compression test. We used only the long block. And used the other parts from the original engine. Radiator was replaced before I got the car. Additional work at the time of engine swap was, water pump, power steering pump and fluid lines etc.
I became worried about the cooling system as the gauge will rise slightly above the “N” at times and then cool back off while driving. It seems to move around more than it should. The warranty on the motor expires at the end of April. Yikes!
I became worried about the cooling system as the gauge will rise slightly above the “N” at times and then cool back off while driving. It seems to move around more than it should. The warranty on the motor expires at the end of April. Yikes!
Joined: Feb 2010
Posts: 28,754
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From: Adelaide Stralia
Oops.
Stats stuck, or wrong stats.
Remove the cap from the steel header tank, insert a syphon hose and DRAIN that tank. It does NOT drain with the cooling system, that feature was only on the PreHE cars.
Then fill the system SLOWLY via the centre stand pipe, and watch and wait for the gurgling to settle. The fluid will run out of the steel tank spout first, then the radiator bleeder, then the filler stand pipe.
Add to the possibilities:
The RH banjo bleeder bolts and associated pipes across the top are blocked, COMMON. It will NOT bleed if this not 100%, fact.
The heater tap is not dropping to the default ON position, thus trapping copious amounts of air in the heater core. OR, the heater core is blocked.
I NEVER run the engine until I have filled the system and fitted both caps.
This is my way for what its worth.
Bleeding the V12 cooling system.doc
Stats stuck, or wrong stats.
Remove the cap from the steel header tank, insert a syphon hose and DRAIN that tank. It does NOT drain with the cooling system, that feature was only on the PreHE cars.
Then fill the system SLOWLY via the centre stand pipe, and watch and wait for the gurgling to settle. The fluid will run out of the steel tank spout first, then the radiator bleeder, then the filler stand pipe.
Add to the possibilities:
The RH banjo bleeder bolts and associated pipes across the top are blocked, COMMON. It will NOT bleed if this not 100%, fact.
The heater tap is not dropping to the default ON position, thus trapping copious amounts of air in the heater core. OR, the heater core is blocked.
I NEVER run the engine until I have filled the system and fitted both caps.
This is my way for what its worth.
Bleeding the V12 cooling system.doc
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