Hi,

I’m facing constant problems with my car and they seems repeating again and again after fixes. The frequent visits to the workshop is burning a lot of my time and money and its really frustrating and tiring.

I have a 96 Jaguar X300 XJ6.

First, It had the coolant hoses giving way and resulting the car stalling. I replaced all the hoses.

A month later, the hoses gave way again with engine overheated. I did a top overhaul, replacing gaskets and plugs, and changing all the hoses again.

Two weeks now, the Fuel Consumption is abnormal, almost doubled, slight petrol smell when I stand outside of the car. No petrol smell in cabin. The Coolant Light is also showing now. I checked the coolant tank and level obviously has dropped. There are signs of leakage at one of the hose end. (Photo attached).

The problems seems to be going in cycles and its frustrating. I’m thinking of having one good fix of every possible problems once and for all.

I’ve googled and items that seems necessary to change new are, O2 Sensors, Coolant Temp Sensors, Air Filters, Coolant Tank, MAF Sensor(cleaned or replace), Fuel Level Sensor(gauge sticking) and Fuel Pump.

I hope you can share your knowledge with me the possible problems and recommendation. I hope to minimise the time the car has to be in the workshop, so I dont mind changing old parts to new even they are working now.

Thank you.

 

Throttle Potentiometer Sensor, or TPS. It was the source of my overfuelling, even though if bench tested well.

add that to the list.

I would replace oxygen sensors, coolant temp sensor and the TPS. Spray some MAF cleaner on the MAF, and close the book on that.

Next up would be to replace the spark plugs and coils. All six of them. If you find oil in the spark plug wells, which you might, I’d replace the camcover gasket as well.

On an unrelated topic, I’d make sure the fuel filter was changed as well.

 

There appears to be a lot of corrosion around that coolant hose fitting. When you next replace it, I'd recommend cleaning as much of that corrosion off of the mating surfaces if you haven't already. That can be a cause of ongoing coolant leaks as well, no matter how tightly you fit the hoses.

Do you have any engine codes present versus guesswork? Guessing can be expensive, and frustrating.

 

Hi Huat,

Surely you don't mean that every coolant hose you replaced failed? If coolant is only leaking at the water pump housing fitting shown in the photo, I agree with Al that the fitting appears corroded. It is not uncommon for the metal of the fitting to erode away on the pipe section over which the hose fits. It is sometimes possible to help the hose seal by applying a good RTV silicone sealant to the pipe before fitting the hose, but if the pipe is too badly eroded you may need to replace the water pump.

Regarding your fuel economy, probably the number one cause of reduced economy is a stuck-open coolant thermostat, which prevents the engine from reaching full operating temperature and causes the ECM to continue applying cold-start fuel enrichment even after the engine should be at full temp, leading to rich running and wasted fuel. If you didn't replace the thermostat while doing the hoses, it should be replaced when you repair the leak. If you replaced the thermostat, did you select one with the correct temperature? According to the Workshop Manual, the OE thermostat is rated at 88C/190F, but lower-temperature options are available on the aftermarket. Is it possible you installed a lower-temp thermostat, or that the thermostat was mistakenly left out when the hoses were reinstalled?

The second most common cause of reduced economy is the Engine Coolant Temperature Sensor (ECTS). If the sensor sticks at a high resistance, or its electrical connector is corroded or disconnected, or a wire in its harness is broken, the ECM will interpret this high resistance as cold coolant temperature and will continue to apply cold-start fuel enrichment just as if the thermostat is stuck open. You can test the resistance of your ECTS when the engine is cold and again when hot and compare the readings to this chart:



Cheers,

Don

 

Judging why the color of the corrosion material, are you by chance running Dex-Cool coolant?

 

Regarding the corrosion on the aluminum fittings. Clean then up real well with a wire brush and smear jb weld on to creat a new smooth surface. Sand if youre not that good with a small spreader. I dont like silicone because ill have to clean it all off when i have to remove again. On my 95 and 96 i switched them both to the later jaguar red coolant. I would look at putting a anode in the coolant to sacrifice that to the metal corrosion gods instead of the engine and everything else aluminum

 

I posted this earlier today in a "constant ticking..." thread in the X-type forum. Sowed a fair amount of hate and confusion, I guess:

Not trying to be a one-chord charlie between this thread and the disabled XJR thread from FL, but doesn't this statement concern anyone else? "First, It had the coolant hoses giving way and resulting the car stalling." Sounds overly hot to me, if it stalled.

Later, OP observes "hoses gave way again with engine overheated." Could just be sentence construction, but this could be interpreted as the engine overheated, causing the hose(s) to blow. Normally, the other way 'round.

I think a compression check of all 6 cyl's may be in order before diving into myriad causes of cold-fueling, though I grant since hoses were changed, the T-stat is a logical check. Just concerned there may be greater damage than assumed due to heat....

I'm not a fan of the (relatively) new website presentation where "Related threads" from various and sundry forums are presented at the end of what you are reading.....guess I'd better tighten up my attention to detail!

 

There is a way to turn off the Related Threads "feature," which I agree is irritatingly imprecise in determining what makes threads "related." Check your User Control panel options - I found a way to turn it off so "Related Threads" no longer appear after threads I have intentionally selected to read.

And good point about the overheating - that caught my eye too but I forgot to ponder its significance to the degree I should have.

Cheers,

Don

 

Thanks much, Don! In case there are other lost souls, such as myself:
User CP/ Settings&Options/ Edit Options
Then scroll down to "Thread Display Options" and the enable/disable box for related threads is the last box in that group.
Continue scrolling after making your choice and hit "save changes" at the bottom.

Bob's yer uncle! No more "related" threads!!!