Hi there,

I'm starting to think I have the beginnings of a head gasket problem on my 1997 XJR. I've been getting a low coolant warning flash up a few times recently and, sure enough, when I have checked the level in the reservoir it has been down slightly. I have also noticed on occasion a spot of coolant on the road directly beneath the overflow. No other symptoms as yet though, so I think I've caught it early. I've seen these gasket repair sealants on ebay, eg. Hyper Seal "liquid metal sealant." Has anybody here tried these? Are they any good?

Experiences and opinions appreciated. Thanks.

 

Start with the simple stuff first. Check your oil and see if it is milky and above the full mark. If so, then it is the head gasket. With the age of your car, check all your hoses carefully. You might find one that is spongy and leaking from an inaccessible area at a connection. That happened to me from an L-shaped main hose that ran from the block to an aluminum tee connection. My leak ended up on the ground above the coolant reservoir tank, but traveled under the supercharger and was very difficult to see and baffled me for awhile. Another thing to check is the coolant reservoir cap is still good.

I do not recommend using those coolant sealers. They may short term fix your leak, but you will have problems of possible engine overheating when it coagulates inside the radiator passages. Then you are in real trouble and need to backflush the radiator and may not get it all out.

 

+1 on XJR Pilot's recommendation to carefully check for a coolant leak, which is more likely than a failing head gasket.

And in addition to the coolant additives plugging up the radiator, a possibly even greater risk is plugging the heater core, where the passages may be even smaller. Years ago, Jaguar actually recommended the use of Bar's Leaks with each coolant change, but at some point, I think during the XJ-S/XJ40 years, they discontinued that recommendation.

Please keep us informed - I hope you find the leak in an easy-to-replace hose!

Cheers,

Don

 

I too would be checking every pipe , hose clip , waterpump &frost plug
Befor adding any chemical to your engine !
I've used (iron tight) in the past my self 4 times on some
Crapy cars and an Isuzu diesel 4x4 in the past with head gaskit issues ,
and had perment Success with three of them and the other took two goes then after wile
Blew up it was no great loss ! Two bottles of iron tight got me 18monthes extra
Life out of it .
Never blocked any thing else but the compression to water sistum
Leak on all occasions ! Has to be done via the instuctions to the word ,
Ie after 1week with chemical in drop water out at running temp !
The oxegen sets the chemical to solid permenent structure!
I have a freand who used it to fix a cracked head In witch
Is bolted to his $700hp GtR r32 skyline, because of the extent of it's porting
Was the only way to fix it without porting another head for $4000!
So he gave it a go and is still holding together 18 monthes later many ks and several
Drag meetings ! I'm sold on the stuff ! It realy is for cracks or seeping , not
For major blow outs ! And I'm sure it won't fix every scenario !
But has been good to me ! I'd put it in my jag it doesn't seem to harm
Any thing , however do not ever use chemiweald!!
That stuff will get you home . Then you might as well bin the engine !
That stuff does not come out of block in an acid bath then it will recirculates it's red
clay like muck to Block everything at running temp after your rebuild !
Not flash ! Iron tight is the only one I'd touch, do not confuse it with any other ,

 

You mention seeing some coolant under the overflow tank. That could be an indication of a faulty pressure cap. It's an inexpensive item and I would replace that and see if the coolant loss stops.

 

Thanks chaps, for these detailed replies!

Definitely worth checking all hoses etc. for leaks - and I shall do that.

I should explain that what leads me to suspect the head gasket is the cooling system is pressurizing: following a fast run on a hot day about a month ago I parked the car, switched off, and about a minute later noticed coolant spewing out on to the road below the radiator.

Suspecting a burst hose, or the rad. itself, I immediately checked but all there seemed good. I then discovered the coolant was coming from a long thin overflow pipe running down from the coolant reservoir, which terminates near the radiator. The fact that the reservoir cap held firm throughout this episode suggests to me it's holding pressure. At the time I thought (hoped) perhaps I had previously overfilled the reservoir and that this was simply the excess blowing out.

Since then I've had no more dramas, but I have got the 'low coolant' warning three or four times, and had to top up on each occassion. And the only place I have ever seen lost coolant leaked on to the road surface has been directly beneath that overflow - although never more than a spot.

I have used Barrs Leaks on a Ford Granada and an Opel Monza many years ago, but never with lasting success. I had hoped that in the 20+ years since then liquid sealant technology might have moved on a bit! But I'm always wary of this stuff simply gungeing up the rad or the heater matrix - giving more problems for the future.

I think in the first instance I will check for obvious leaking hoses etc. but then take the car to my local garage to test for exhaust gasses being present in the coolant. Visually, the oil and water both appear clean and uncontaminated.

But many thanks again for all this advice. I'll let you know how I get on.

Cheers,
John.

 

Often, too often in fact, folks misroute those thin black plastic overflow pipes: the one going to the radiator should be closer to the left side of the car; the one going to the overflow bottle under the fender should be in board (to the right) of the first. When they are not connected correctly (crossing over), they create an overpressure which blows steam. Lots of threads on this forum that show the right way.

This assumes you did not break the coupling at the hose that was blowing: if so, ~30 pounds buys a new one. They are fragile.

Good news, tho; I doubt it is a head gasket.

 

jhartz,

I too have experienced a very small drop in coolant requiring I add about 2 ounces per month. Your post regarding the proper connections for the coolant lines may have just solved my problem.

I have attached a picture. Hopefully you can use your familiarity with the X308 engine compartment to orient yourself. It appears to me that the connections are the opposite of what you stated as correct in your post.

Can you help me confirm that they are backwards? Also, would this account for my slight coolant loss? Also, will switching them correct my problems with no likely damage done thus far?

The engine was replaced just before I bought the car, so they've possibly been connected incorrectly since December 2014 (about 7,000 miles of driving). If I switch them back, should I have anything else to worry about regarding this?

Thanks much,
Jeff

 

They look the wrong way round to me. I'm pretty certain that there is a diagram somewhere on the forum if you search for it.

 

Yes, I responded as an excited impulse but I then proceeded to search. It DOES appear someone attached mine incorrectly.

I just went out and switched them. Those connectors will never win "Design of the year" because the threshold between what it takes to remove them and what it takes to break them is very thin! haha. Fortunately though, I did not break them.

So my only remaining concern is ; "did that cause any permanent damage?".

--- I thought I would share how I finally removed the connectors. I used snap ring pliers (external? the ones that open outward) and pulled gently while the pliers were expanding the fitting. They came off perfectly. In the future I will hopefully not experience any more frustration when working with this kind of connector.

 

I had a little leak also and was having a hard time finding it so I wanted to purchase a coolant pressure pump,it's a simple hand operated pump with all the different adapters to fit the different cooling systems. Not only did I have a hard time finding one but when I did it was over two hundred bucks!! So I was at our local hardware store and saw bicycle pumps on sale and thought I could plumb it into the top line of the coolant resivoir tank,it even had a gauge on it and it worked fine. Caution if you do this don't go over 20 ibs . I don't think I had 10 ibs in there and found my leak,it was an easy fix on the heater hose.

Randy

 

H14: yep, from your photo they need to be swapped. I use long needle nose pliers to relieve pressure on the fittings (an aside, these cars were shipped with the tool tied somewhere around the radiator; dealer techs often forgot to put them back: I can't remember if it was Bob or brutal said they had a whole toolbox full of them). I don't think you have done any damage. I would buy an OBD two reader that will show engine temperature real time; keep connected as you drive and keep an eye on the temperature.

v8 duece: howza bout a picture of your plumbing: what a great idea you had.

 

I've been checking around the externals for any obvious coolant leaks. Pressure cap on the expansion bottle by the bulkhead now replaced with new. My question is: how do I gain access to the overflow bottle (header tank) just ahead of the N/S/F wheel? I just want to make sure that the thin black overflow pipe is actually connected...

Advice - as ever - appreciated!

 

Anyone ever change a head gasket on a 96 XJ6 4.0L?

 

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