Coolant system pressure test
#1
![Default](/forum/images/icons/icon1.gif)
2004 XJ8 with 4.2. I have a slight cooling system leak. There is no obvious leak. I used UV dye and the got a hit on the water pump. I replaced the radiator and water pump. System will still not pressurize with a tester. I am thinking the heater core or the aux heater pump. Never had a aux heater pump so don't have any experience with that. I assume the system should hold pressure? Agreed? Suggestions please.
#2
![Default](/forum/images/icons/icon1.gif)
God forbid it be a small leak in the valley hose. Did you look for a leak down back of the engine/trans? It's very hard to find, the dye will help. Most cars leaks are in the front area, heater hoses, as were you first checked. But ours also has a prone area we ALL don't want to find leaking.
I hope its not that.
Mark
I hope its not that.
Mark
#3
![Default](/forum/images/icons/icon1.gif)
I had a persistent coolant leak. It looked as if the radiator was leaking, so I changed with new hoses. But the leak persisted. A test showed I was burning coolant out the exhaust. Not good news - either intake or head gasket (quote $3800 to replace). Tried a $20 can of high quality sealant, which seems to have stopped the leak. So you might have your coolant system tested for leaking into the engine and then burning out the exhaust.
#4
Join Date: Feb 2014
Location: Crossroads of America
Posts: 19,581
Received 13,203 Likes
on
6,552 Posts
![Default](/forum/images/icons/icon1.gif)
2004 XJ8 with 4.2. I have a slight cooling system leak. There is no obvious leak. I used UV dye and the got a hit on the water pump. I replaced the radiator and water pump. System will still not pressurize with a tester. I am thinking the heater core or the aux heater pump. Never had a aux heater pump so don't have any experience with that. I assume the system should hold pressure? Agreed? Suggestions please.
Cheers,
Don
#5
#6
![Default](/forum/images/icons/icon1.gif)
Correct. The Valley hose applies to supercharged engines only. Stock XJ's will not have this issue.
The following users liked this post:
Don B (03-07-2017)
#7
![Default](/forum/images/icons/icon1.gif)
2004 XJ8 with 4.2. I have a slight cooling system leak. There is no obvious leak. I used UV dye and the got a hit on the water pump. I replaced the radiator and water pump. System will still not pressurize with a tester. I am thinking the heater core or the aux heater pump. Never had a aux heater pump so don't have any experience with that. I assume the system should hold pressure? Agreed? Suggestions please.
The following users liked this post:
Don B (03-07-2017)
Trending Topics
#8
#9
#10
![Default](/forum/images/icons/icon1.gif)
Thanks for all the advice. I removed the intake manifold and replaced the valley hose. The engine starts and idles fine but now I get a "RESTRICTED PERFORMANCE" message. Code P0117 coolant sensor. The temperature gauge will go HOT very quickly. Too quick, the engine hasn't had to time to get warm. I guess there must be air trapped in the system. I removed the bleeder plug when I filled it. I had the throttle body off maybe that has something to do with it.
Is there something special you have to do to bleed this?
Also the car will not shift out of 1st gear or speed up. I assume it has gone into some "LIMP HOME MODE". I am assuming (hoping) that once I get it bleed everything will run fine. What do you guys think?
Is there something special you have to do to bleed this?
Also the car will not shift out of 1st gear or speed up. I assume it has gone into some "LIMP HOME MODE". I am assuming (hoping) that once I get it bleed everything will run fine. What do you guys think?