Thermostat Housing Leak...Help!
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Thermostat Housing Leak...Help!
I have a 98 XJ8L and I noticed that I have a slight leak at the bottom of the thermostat housing. If you fill up the reservoir and drive it daily, the low coolant light will come on in about a week. Should I try to tighten the bolts? Do I need a part to fix this? How hard of a job is it to fix? Is there any stop leak I can use?
Also, it appears that I have green coolant in the radiator. Do I need to change this out with the Jag coolant?Thanks guys, any help will be greatly appreciated.
Also, it appears that I have green coolant in the radiator. Do I need to change this out with the Jag coolant?Thanks guys, any help will be greatly appreciated.
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RE: Thermostat Housing Leak...Help!
It sounds like the thermostat gasket needs replacing and I would replace the thermostat at the same time. It shoud be pretty easy to do but probably no to expensive to have done either as long as you don't have to take it to the dealer. As for the green coolant it's ok as long as you don't mix it with the orange stuff.
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Joined: Oct 2007
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From: Lakewood, CO
RE: Thermostat Housing Leak...Help!
badmojo's advice is right on. If your green coolant is more than 2 years old, this is the time to change it. If you decide to go for the long-life antifreeze, most of the new stuff will mix with all colors and all types, check the label. This way you can avoid a complete flushing if so desired.
Doug
Doug
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RE: Thermostat Housing Leak...Help!
I'm in the middle of this job right now. Things were going well until I found out that the end of the coolant rail had broken off inside the radiator hose. Looks like another part to buy and more down time...my undying gratitude to Jaguar for using so much plastic in and around this engine.
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RE: Thermostat Housing Leak...Help!
Another thing - You may have a devil of a time getting the rear bolts off. The quarters are very tight, and there is little clearance both above and behind the bolts. Forget usinga socket or a ratcheting box end wrench.
Joined: Jan 2008
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From: 33498
RE: Thermostat Housing Leak...Help!
If you have a leak, probably better replacing the thermostat housing instead of just the gasket. As you said, it is plastic and the part is cheap. Better for piece of mind.
The two 8mm bolts at the back of the t-stat housing do come out. Easier to use crows foot. Do yourself a favour, when you put it back in, use two of the bolts that hold on the thermostat cover. They are a tad bit shorter and therefore easier to start at t-stat housing. Just replace the two in the cover with the back two from housing.
Also, once you get it running, bring up to about 3000 rpm and hold there with heater on until it gets up to operating temp. This will allow any air pockets to pull through t-stat.
After it cools off recheck coolant level.
The two 8mm bolts at the back of the t-stat housing do come out. Easier to use crows foot. Do yourself a favour, when you put it back in, use two of the bolts that hold on the thermostat cover. They are a tad bit shorter and therefore easier to start at t-stat housing. Just replace the two in the cover with the back two from housing.
Also, once you get it running, bring up to about 3000 rpm and hold there with heater on until it gets up to operating temp. This will allow any air pockets to pull through t-stat.
After it cools off recheck coolant level.
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Joined: Jan 2008
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From: Limbo
RE: Thermostat Housing Leak...Help!
FJT - you are an incredible asset to this board (I've been lurking for a while - my first post now)!
In keeping with your motto -"If it ain't broke...." - I have kept a new t-stat in the boot of my 107,000 mile, trouble-free 1999 XJR in case the original goes bad, but haven't installed it. In the past, I have done "preventive" t-stat changes on cars, only to have the new one fail shortly thereafter.
In the same vein, the original secondary tensioners looked fine when I pulled the cam covers, and the car has never been overheated, regular Mobil1 changes at 5K miles since I bought it new. Am I foolish to leave well enough alone for now? The car runs as well as the day I bought it....?
________
1999 XJR
In keeping with your motto -"If it ain't broke...." - I have kept a new t-stat in the boot of my 107,000 mile, trouble-free 1999 XJR in case the original goes bad, but haven't installed it. In the past, I have done "preventive" t-stat changes on cars, only to have the new one fail shortly thereafter.
In the same vein, the original secondary tensioners looked fine when I pulled the cam covers, and the car has never been overheated, regular Mobil1 changes at 5K miles since I bought it new. Am I foolish to leave well enough alone for now? The car runs as well as the day I bought it....?
________
1999 XJR
Last edited by joycesjag; Nov 25, 2012 at 08:46 AM.
Joined: Jan 2008
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From: 33498
RE: Thermostat Housing Leak...Help!
As the motto says......
I always love to hear about the good ones. If your vehicle is running well, leave it be. If the chains or tensioners go, you will normally know before hand. Also, it is not an interferance motor, so even if they went as you were driving, just shut it off. There shouldnt be any damage to the engine. I have only seen once where the valves rapped off the piston, that also was due to overheating.
I too own a Jaguar. 2001 VDP. Wonderful cars in my opinion. As long as you maintain and do some PM, they will last for years to come.
I always love to hear about the good ones. If your vehicle is running well, leave it be. If the chains or tensioners go, you will normally know before hand. Also, it is not an interferance motor, so even if they went as you were driving, just shut it off. There shouldnt be any damage to the engine. I have only seen once where the valves rapped off the piston, that also was due to overheating.
I too own a Jaguar. 2001 VDP. Wonderful cars in my opinion. As long as you maintain and do some PM, they will last for years to come.
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RE: Thermostat Housing Leak...Help!
FJT: Thanks for the tip on the bolts. I am still trying to get mine off (everything else was relatively easy). I am having an awful time finding an 8mm crowfoot. Virtually all of the sets I have found start at 10mm, and the one set I found with an eight has an extension that partially wraps around the back of the nut - leading me to believe that I would have the same clearance problem I had with the ratcheting wrench.
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RE: Thermostat Housing Leak...Help!
All the parts for this job cost around $130 at Motorcars, Ltd. (http://www.motorcarsltd.com). This includes the thermostat housing, thermostat cap, thermostat housing cover, thermostat with gasket and necessary gaskets for the thermostat housing and water outlet pipe (which you will have to remove to get the housing off). If you need a new water outlet pipe (mine wasbrokeninside the radiator hose), that is about $44 more. There is free shipping on orders over $100, and the people there are very helpful by phone or e-mail.
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From: 33498
RE: Thermostat Housing Leak...Help!
If you cant find one, you may have to take off the intake manifold. Very easy to do. While you are in there, change the heater hoses. Better again to do some preventive maintenance. Once the intake manifold is off, you have full access to the bolts on the T-Stat housing.
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RE: Thermostat Housing Leak...Help!
Thanks for the advice, once again. Will I need any other parts (gaskets, etc.) before I replace the intake manifold (if I go that way)?
I may have found an 8mm crowfoot at Snap-On Tools. $15 seems a little pricey for a single wrench, but I'm tired of getting nowhere.
I may have found an 8mm crowfoot at Snap-On Tools. $15 seems a little pricey for a single wrench, but I'm tired of getting nowhere.
Joined: Jan 2008
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From: 33498
RE: Thermostat Housing Leak...Help!
Cheaper to have that tool than to remove intake.
If you take off the intake manifold, you will need intake manifold gaskets and throttle body gasket. You will also need fuel line disconnects. If you follow your way around manifold slowly, it is pretty easy. Time consuming.
I personnally would go the crows foot way. $15 for the crows foot. Welcome to my world. Easily have $65,000 in tools and tool box. People don't realize how much of an investment we have to make to go to work every day.
Good luck. If you need any more help ask.
If you take off the intake manifold, you will need intake manifold gaskets and throttle body gasket. You will also need fuel line disconnects. If you follow your way around manifold slowly, it is pretty easy. Time consuming.
I personnally would go the crows foot way. $15 for the crows foot. Welcome to my world. Easily have $65,000 in tools and tool box. People don't realize how much of an investment we have to make to go to work every day.
Good luck. If you need any more help ask.
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RE: Thermostat Housing Leak...Help!
Thanks. I ordered the crowfoot rather than take half the engine apart. It didn't arrive in time for me to finish the job this weekend, but hopefully will be here sometime early next week.
As always, FJT, I appreciate the advice.
As always, FJT, I appreciate the advice.
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RE: Thermostat Housing Leak...Help!
The crowfoot wrench was the magic bullet. Within five minutes I had the old thermostat housing off. The installation went very smoothly, and upon runup and pressurization there were no apparent leaks and the car does not overheat. I also followed your tip about using the thermostat cover bolts on the back when mounting the new thermostat housing, which I believe made the installation go much more smoothly than it otherwise might have.
From visual inspection it appeared that the old thermostat housing and thermostat were fine. There were no visible cracks in the housing. The seal at the bottom obviously failed. It appeared distorted, and there were deposits underneath it which I had to clean off before putting the new housing on. This indicated to me that the seal had probably been leaking for a while before it failed to the point that I was spewing coolant like a creek. Since I already had everything apart I don't regret spending the money to replace all that plastic. Now it should be good for a while. The coolant rail was already cracked at the end, and the thermostat housing might not have been that far behind had I not changed it out.
My primary advice to anyone changing out a thermostat housing is don't even try it without an 8mm crowfoot wrench.
The cooling system seems to work fine now. However, I have a new problem now that I will detail in another post.
From visual inspection it appeared that the old thermostat housing and thermostat were fine. There were no visible cracks in the housing. The seal at the bottom obviously failed. It appeared distorted, and there were deposits underneath it which I had to clean off before putting the new housing on. This indicated to me that the seal had probably been leaking for a while before it failed to the point that I was spewing coolant like a creek. Since I already had everything apart I don't regret spending the money to replace all that plastic. Now it should be good for a while. The coolant rail was already cracked at the end, and the thermostat housing might not have been that far behind had I not changed it out.
My primary advice to anyone changing out a thermostat housing is don't even try it without an 8mm crowfoot wrench.
The cooling system seems to work fine now. However, I have a new problem now that I will detail in another post.
Joined: Jan 2008
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From: 33498
RE: Thermostat Housing Leak...Help!
Glad that you got it sorted. Always worth while if you are in there to replace that plastic. Alot of the time you cannot see the crack in the thermostat housing. It just kind of seeps through it.
I replied to your other post about the RP light.
I replied to your other post about the RP light.
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Joined: Apr 2008
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From: Richmond Hill, Georgia
RE: Thermostat Housing Leak...Help!
I've got a 2001 XK8 that appears to have a crack in the plastic thermostat housing. I found the aluminum replacement kit at Motorcars LTD for $84.19. I'm going for the 8mm crow's foot, now! The engineers at Jaguar really ought to consider some more robust design approaches, considering they are trying to counter their history of questionable reliability. Speaking from an E-type owner, and Mechanical Engineer working for Gulfstream Aerospace Corp.! Lightweight design is important, but reliability is MOST important.
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RE: Thermostat Housing Leak...Help!
The crowfoot took a long time for me to find. The one I bought was from Snap-On Tools. This is it:
http://buy1.snapon.com/catalog/item....mp;dir=catalog
http://buy1.snapon.com/catalog/item....mp;dir=catalog