My car started loosing a little coolant, but I couldn't see anything leaking. Then I noticed that when the engine gets revved up a bit whether cold or warmed up, the upper radiator hoses balloon out and you can feel the pressure increase as the rpms go up. Is this normal? Has anyone ever heard of this? I'm going to have the coolant checked for exhaust gases Monday. The oil is clean, no coolant in there. The car hasn't gotten hot in years and the car drives fine and everything works normally. Is it some air in the system or I dread to ask, a blown head gasket?

 

Normalish. My first thought is the hoses are starting to go.

When you rev the engine, coolant flow from the water pump will increase. The radiator is a fixed restriction. Any part of the cooling system between the water pump and radiator will be subjected to increased pressure. If the hoses are marginal, they will swell.

For peace of mind, do a cooling system pressure test. This is the tester that connects in place of the reservoir cap and looks like a bicycle pump. Pump up the system to the rating on the cap and make sure the pressure holds for at least 15 minutes.

You can also do the test for exhaust in the cooling system, if still concerned. This is the turkey baster doohickey that draws a sample of air from the top of the reservoir. The tester has a special liquid that changes color in the presence of exhaust gases.

Don't go into FullPanicMode just yet, though. The symptoms sure sound like old hoses on their last legs.

 

Thanks for replying kr98664, I know one person that has an S Type with a 4.2, I'll go check it out on his car and see what the hoses do when it's revved up. The upper radiator was replaced a few years ago on my car and it acts and looks and feels the same as the twenty year old main hose attached to the thermostat housing. The pressure increase seems a bit much to me, I hope not.
If it turns out to be normalish, do the spring clamps weaken over time, because they are all original? The leak seems to be from the pressure forcing coolant past the spring clamp at higher revs. Would it be better to replace them with new spring clamps or the wormdrive style that you screw in to tighten?

 

If you replace the hose clamps, use only constant tension style clamps. Do not use jubilee or worm type clamps on any hoses that meet with a plastic pipe as they can cause the plastic to fail.

You can also pressure test the cooling system when cold to determine if the issue is a weak hose.

 

Thanks for the reply NBCat, do the original spring clamps weaken with age? Do you mean spring clamps when you say constant pressure clamps or something else? Should the pressure in the main hoses increase quite a bit when the engine is revved up or ran at higher rpms or stay about the same as when running at lower rpms?

 

When you do the pressure test, also take a flashlight, or trouble light and check the crimped areas where the side tanks are attached to the radiator core. Coolant can very slowly seep from these areas and will evaporate not leaving the tell-tale drips on the ground. Your coolant in the reservoir will slowly go down and nothing else will appear amiss...

 

Hi Catmobile,

As Karl has already noted, since your engine uses a conventional mechanical water pump, it is completely normal for the coolant pressure to increase when the engine is revved, since the pump impeller speed is directly proportional to engine speed. The radiator hoses will feel more rigid, but should not balloon outward from their static cylindrical cross section.

A very common leak point on these engines is the water pump. Coolant seeps out of the weep hole or around the shaft onto the hot engine and evaporates, so you don't see any drips on your garage floor or driveway. Often, a water pump leak will not show up during a pressure test, so I use an endoscope to inspect the area directly below the water pump and behind its pulley. Coolant residue is usually very obvious.

P.S. I deleted your new thread on this same topic and will glady revise the title to this thread if you will respond to my PM.

Cheers,

Don

 

When doing the pressure test, be sure to test the cap, too. Make sure it is venting at the rated pressure. If it needs to be replaced, be sure to test the new one, too.

Any time I've seen a swollen radiator hose, it was the hose succumbing to old age. Test the cap in the slim chance the pressure is building too high. But if the existing cap is good, I wouldn't worry about a bad head gasket, etc. A properly functioning cap should have relieved pressure long before a good hose ballooned out.

 

Thanks for the replies. The hoses don't really balloon out like blisters, they just inflate a little more than when idling but still keep their shape, but you can feel a lot more pressure in them at higher revs. My big questions are, is it normal for the main hoses to have quite a bit more pressure that you can feel at higher revs than at low revs or should they feel about the same? Next question is do the original spring clamps lose their grip after twenty years and should be replaced, or should they still hold? The upper radiator hose, the water pump, and the radiator are just a few years old, but the spring clamps are original. Or I'll sneak in one more, could air in the system cause this problem? I had the cap tested and it releases pressure like it should. Tomorrow I'm going to have the coolant checked for exhaust gases, but they don't know much about Jaguars or how the hoses should or should not feel. I'm just wondering if it's a big problem or that I just need some new hose clamps to stop the leaking. Thanks again, Elliott.

 

There is nothing unique about pressure testing a Jaguar X200 cooling system. Any competent repair workshop should be able to perform the test regardless if they work on Jaguar vehicles or not.

The clamps do not 'weaken' over time. Below is an example of a constant tension hose clamp similar to the original ones fitted to your vehicle.

 

The spring band hose clamps are fairly expensive to replace and not widely available, so it's a good thing that they do not tend to lose their tension over time. I do replace one if it is heavily rusted, and the easiest place to get the correct size is from a Jaguar dealership or online Jaguar parts vendor.

 

You guessed it, Don. It's the water pump, just a minor crisis and not a major crisis like the head gasket. I replaced the water pump November of 2021, not too long ago, I'm checking into it but I think it has a two year warranty. No more cheapo parts for me, especially ones that are difficult to replace.
Thanks for all the feed back. The truflo water pump at NAPA has a limited lifetime warranty, hopefully it will last longer than the eurospare or airtex or whatever it was that I got last time.
Elliott