Coolant level sensor

[Vernon]

Hi guys

XJ Cherokee 2.5diesel - I think the float in the expansion chamber has a leak and has sunk - giving a false reading.

 

Does anyone know if the float sensor is removable?  I have found one that looks like it would fit but it’s listed for a Grand Cherokee.

 

The one in my XJ looks very snug in the expansion tank.  

 

 

[V]

I didn't know there was a coolant level sensor on a diesel XJ. I couldn't find a part number for it or the bottle. I found the parts diagram for the diesel xj bottle on the hoses page, but not the part number.

 

[Vernon]

Thanks V - I’ll take some pics and post what I have.

 

Tho bizarrely it’s all back and working now - so there is an intermittent fault.   It was not working at all initially and I too thought it didn’t even have a level sensor and then I found what clearly was one on the expansion chamber.

 

Cleaned up the contacts and hey presto!  A nice Red Radiator display popped up next to the “Check Gauges” warning on start up.

 

Then last week it stayed on despite the level actually being fine.

 

Yesterday I disconnected and reconnected and it came on on start up - then went out as it should.

 

So sorted - for now - and glad it “fails safe” - rather have a false low coolant warning than it not bother telling me I’m losing coolant.

 

It’s not helped by the expansion chamber being totally opaque!  Cannot make out coolant level at all.  Which everyone says is a common problem.   But I’m working on a solution.

[Vernon]

Some pics

 

The sender plug is at the bottom of the exp/tank

 

The coolant level is fine but with such an opaque tank it’s very difficult to judge - so tendency to overfill.

 

I am considering a T piece in the narrow gauge tube from the radiator top - fitted adjacent to the tank - connecting via a see through tube to a second T piece placed in the narrow gauge tube from the top of the engine.

 

I cannot see how (as long as all connections good) this would compromise coolant flow in anyway as these outlets are connected via the opaque tank anyway.

 

And a secondary clear connecting tube would show the coolant level.

 

Any thoughts guys?  Am I overlooking an obvious flaw?

 

My thoughts are that if it all goes horribly pear-shaped it would be easy to reverse back to standard.

[V]

The bottle must have changed over the years. Having never owned a diesel XJ I am not as familiar with variants as I am with the 4.0L .

 

Here is a screen grab from the parts catalogue showing the diesel coolant bottle. Even though the bottle is shown in the catalogue, there is no part number for it. The diagram doesn't show a low level sensor either.

 

[Vernon]

Many thanks - that would explain why I was having real problems finding anything on coolant level sensors.

interestingly there is a US YouTube video on how to fit a sensor for a 4litre - but nothing at all for a TD.

Yet again - the joys of this “run out” 1996 TD which not only gave us issues on the belt tensioner but the coolant sensor as well.

 

Still - the good news is the New Nissens Rad and Nissens A/C condenser are fitted, the engine runs cooler (I would say the size of the rad - especially the side tanks - is at least 20% larger that the original rad I took off - and that rad was totally shot!!

[Vernon]

1 minute ago, Vernon said:

Many thanks - that would explain why I was having real problems finding anything on coolant level sensors.

interestingly there is a US YouTube video on how to fit a sensor for a 4litre - but nothing at all for a TD.

Yet again - the joys of this “run out” 1996 TD which not only gave us issues on the belt tensioner but the coolant sensor as well.

 

Still - the good news is the New Nissens Rad and Nissens A/C condenser are fitted, the engine runs cooler (I would say the size of the rad - especially the side tanks - is at least 20% larger that the original rad I took off - and that rad was totally shot!!

 

[Vernon]

Apologies sausage fingers !!

 

Being gassed up tomorrow So barring leak issues - I should be nice and cool during the upcoming apocalypse.

[Vernon]

Happy to say - all gassed up nicely - no leaks (Tho’ time will tell) and lovely cold air on tap when needed.

 

Role on that heat wave!

[digger]

Hi Vernon, I had a '98 XJ 2.5 diesel and am not aware/do not recall that it had  a coolant level sensor. Not a bad idea though. Some of these engines have head gasket problems. The root cause in my opinion is  cast block/alloy heads. Nothing wrong with that but it needs good maintenance,  especially the correct antifreeze to avoid corrosion plus avoid  over revving/overheating and then there should be no issues. So your mods should be good! You can chip these up too!

  I like your  'coolant level view tube' idea as well . My Yj is the same, even with the bright pink A/freeze I can't see much.

Hope this helps.

I can't see why people rev these motors they have gr8 torque! I remember the first time I went to Tuff Terrains. Bernie(the site owner) said it was the first one he had seen and asked me to see if it would go up a particular hill on tickover. It did !!!  

[Vernon]

On 06/08/2022 at 18:02, digger said:

Hi Vernon, I had a '98 XJ 2.5 diesel and am not aware/do not recall that it had  a coolant level sensor. Not a bad idea though. Some of these engines have head gasket problems. The root cause in my opinion is  cast block/alloy heads. Nothing wrong with that but it needs good maintenance,  especially the correct antifreeze to avoid corrosion plus avoid  over revving/overheating and then there should be no issues. So your mods should be good! You can chip these up too!

  I like your  'coolant level view tube' idea as well . My Yj is the same, even with the bright pink A/freeze I can't see much.

Hope this helps.

I can't see why people rev these motors they have gr8 torque! I remember the first time I went to Tuff Terrains. Bernie(the site owner) said it was the first one he had seen and asked me to see if it would go up a particular hill on tickover. It did !!!  

Oh yes!  My first experience of the VM425 was in a friends Classic Range Rover.  The torque was awesome and way better than the Td200/300.

 

Hence my delight in finding one in an XJ with such a great service history.

 

The Antifreeze issue is one that bothers me as I have had quite a few issues with OAT (the pink one) antifreeze in the past dissolving rubber O rings. Particularly an issue on a TD4 Freelander and the M47R I had in a MG ZTT.

 

I could not understand why the BMW type hose connectors leaked - and then I hooked out an odd looking O ring and it looked like a dog had chewed it.

 

It seems the Organic Acid Technology antifreezes are not good for old motors in this respect - BUT, my mate who I trust - says that OAT is better for alloy heads?????

 

But my understanding was that if air gets into the OAT cooling system the Organic Acid can turn really acidic and eat rubber/gaskets/seals etc.  if true I doubt cylinder heads would appreciate an acid was either….,,

 

So I’m running on Blue (Silicate) stuff at the moment but read on US sites that I should be using “Green” antifreeze.

 

I’ve checked the spec of the blue stuff I’m using and it is what’s listed in the handbook.

 

So any thoughts most welcome.

[digger]

I think you will be fine. its the spec that's important . I just got sucked into the colour myth. The colour doesn't matter as far as I know. Its just that the one I have is pink! Different makes have different colours!

Beamers no comment. I've had 2 new ,1 , 6 month old . Typical unreliable German junk. Looks good on top but living on something they did a long time ago in my opinion!  I  will never buy a German car again , they've all been the same for me.

I think VMs are good engines. They have been much better to me than German engines . The 2.5 diesel was designed for constant speeds in a canal boat. I think that's probably why they don't like being over revved.

[Vernon]

Like many engines - they are susceptible to cooling issues.  And the design on the XJ is not optimum.

Hence my not messing and going for upgrading the rad size.  
So far so good, even after a good run, now the top hose is hot - but the bottom hose cool.   Far cooler than it was before.

 

Thanks for the info on the antifreeze.  Unless I’ve missed something it looks like silicate based antifreeze is Green in the States and Blue in the U.K.

 

Cooling issues I had were blocked narrow bore pipe from top of engine to expansion tank,  slimy rusty crud in the heater matrix and a coolant level sensor with “attitude”.  Plus a rad that was the original and was as rusty as heck.

 

I changed the thermostat as well as I could not make sense of what was happening initially when “burping” it.   

And I drilled a 6mm hole in the thermostat edge and made sure that was at the top of the housing.

 

I also did a favourite trick of mine and cut the top hose roughly in half and inserted a metal tube with a bleed valve.

Makes life so much easier.

 

But the Heater Matrix was not playing ball so cut those feed pipes in half at their highest point and inserted bleed valves which whilst useful in them selves also meant I could a) isolate the heater matrix if it sprung a leak with all my fiddling about and b) give the heater matrix a separate good flush through by attaching a hose to its inlet and not sending the crud round the rest of the cooling system.

 

It worked well as I got a load of slimey goo that popped out on to the driveway that looked a bit like a foot long cats furball that our cats puke up from time to time.

 

Luckily, so far, no coolant leaks into the cabin and coolant level was stable even with the cruddy old original rad.  But then that started weeping and Nissens got another satisfied customer.   The welding on their rad is awesome.

 

Replacing all the hoses is on the list - but they are really good overall and the flushing has cleared off all the rusty crud.

 

Can’t tell you how good it is to check the coolant and find a nice clear blue liquid instead of a cloudy rust coloured one.

 

Ill post some pics of the coolant bleed valves tomorrow.  A cheep and easy diagnostic for cooling issue.

 

I will keep the Top Hose one even if I replace the hoses.  Whereas the heater matrix hoses will probably be replaced whole.

[V]

13 hours ago, Vernon said:

I also did a favourite trick of mine and cut the top hose roughly in half and inserted a metal tube with a bleed valve.

Makes life so much easier.

 

Have you got pictures and are willing to share more info about this mod?

[Vernon]

On 09/08/2022 at 11:03, V said:

 

Have you got pictures and are willing to share more info about this mod?

Yes - sorry, events overtook me yesterday - apologies

 

The pic of the top hose mod is pretty self explanatory and I cannot tell you how useful it is to help rid that nagging feeling re air in the system causing HGF.

 

Interestingly the other pics show the bleed valves in the heater matrix feed tubes that I first came across when playing with Rover K series engines.  Those that really knew about these engines fitted them routinely.

 

The K series is, IMO, a much maligned engine let down by the idiotic placement of the Thermostat and poor cooling system design.

 

I also routinely put a 5 or 6mm hole in the thermostat next to where most manufacturers put the silly little ball bearing valve - which I feel is in chocolate teapot territory.

 

I’ve never really feared an engine running slightly cool.  But one overheating I don’t like at all.

 

Bit like flying - that doesn’t scare me at all.  But the thought of crashing scares the **** out of me.