Ideas?
I’ve had this old girl for a couple of months, she’s been very well kept but today I noticed a bit of a knock/tap. Video link https://youtu.be/a6TU1SOwtyc

2002 Discovery 2, 4.0, 153k miles, noise worse in video than in life, can’t be heard inside.

Previous owner maintained very well, had head gaskets done at a very reputable houston shop recently. Drives perfect, no codes I can read, oil level is just above full with no discoloration.

Sounds like it’s coming off the top, I thought it could be a bearing in the alternator or something for a minute. The cam/roller below the alternator looks to wobble a touch but not sure if related.
Noise is with the engine rpm but not consistent in volume and frequency… sounds a bit like a marble getting knocked.

Any ideas or experience, maybe a point out of where to start before I start pulling her apart?

https://youtu.be/a6TU1SOwtyc

 

Start with using is/is not - Is it doing it cold, or cold and hot? If it only does it hot, what temperature does it start at? Notice the exact temperature it starts. idle only, or idle and at 1500 rpm or some other higher number? Start by removing the accessory belt, does it do it without the belt?

BTW, that thermostat looks like it is ready to crack/explode any moment - you need an inline kit on that thing.

 

Thanks, yeah I guess I didn’t do is/is not because it’s doing it in all conditions.

Noise exists when cold and hot, both starting and running, gets worse under load reduces with load reduction but still apparent, not fully consistent with engine speed but follows it.

Going to pull belt in morning, have limited tools here so was trying to find a good starting point before I get into it. Belt is a good one.

I’m beginning to think it’s the idler pulley/wheel maybe that bearing has seen its last days.

Can you educate me on the thermostat issue you see? Just so I know what you’re seeing and for my reference.
I’ve got the previous owners maintenance records and it’s all been replaced relatively recently, so obviously I’m concerned.

 

Definitely sounds like one of your idler pulleys or the tensioner pulley on the belt. May also be AC compressor, alternator, water pump, power steering or ACE (not sure if you have it, couldn't see), etc.

Easy to diagnose. Take the belt off (fan cowl and fan off) ... then skinny spinny each by hand and I bet you find the issue. Careful you don't knock a hole in the radiator when pulling the fan -- and careful with the plastic water hose that goes from drivers side radiator over to the coolant expansion tank.

Also agree the t-stat looks old ... replace with the grey Genuine LR 180 degree, or do the inline thermostat mod as the gent above me recommends !

 

Appreciate it, I’ll get that belt off tomorrow and have a fiddle about. I don’t think I have the right tools here to get the fan off but if I can give myself the “safe but not ideal to drive” go ahead I can drive it to my workshop when I finish this job.

Will look into the thermostat kits, the issue you see is the apparent age of the plastic?
Houston weather is pretty tough on all plastic especially what we make in England, so I’ll definitely start my research!

 

The thermostat is a rusty brown color, those are white when new. I have seen those at that point at least 10 items, the plastic gets brittle and cracks. The hoses look old too, like they are OEM. Truck is 20 years old at this point, any non-metal piece of the cooling system is either brittle if plastic or soft if rubber. I have cracked radiator end tanks, thermstats, coolant bottles, hoses, and the wye spider in the lower radiator hose. All of those leave you at risk of overheating if it blows while driving. I recommend you replace any of it not replaced in the last 10 years.

 

Appreciated, will digest this, review the service receipts and POs notes (he made a lot) and make a plan to do some preventative maintenance/upgrading here. So I can see what was done and avoid any aftermarket brands that may have been used which already look old enough to be concerned with!!

 

You don’t need to remove the fan to replace the belt.

 

Well I took the belt off and the noise went away, put it back on and it came back.

Idler pulley bearing felt a bit gritty spinning it by hand, nothing else seemed awful.

Except, when I restarted the car, the radiator fan is bouncing all over without the shroud. I don’t observe it touching anything but this can’t be right, I’d guess the bearing or something down there is knackered.

So I’m assuming a water pump replacement, just weighing up whether to do fan clutches as well and also thermostat stuff whilst I’m dropping coolant.

It’s a 100 mile drive to my home with the workshop. I also need to weigh up whether to risk a drive or take my motorcycle and bring a truck and trailer back with me…

YouTube videos:

 

If that fan comes apart due to wp bearing failure it will take out your trans, ps, and oil cooler hoses. Ask me how I know....