To make this easier and because I suck at describing sounds, behold a 26 second video clip:

http://www.youtube.com/watch?v=zqQX6lcfKzY

I heard this sound for a while from the engine of my TR 2.6L Magna Sedan, but as it's been off the road for the last 5 months, I decided to revisit it over the last couple of days. I did some searching around the engine bay and may have found the source, as it seems to be the loudest up toward the water pump belt and pulley.

It's almost a whistling / scraping sound in nature, perhaps the bearings in the pump, I'm not honestly sure at this stage as I haven't had a car reach the point where the water pump may be beginning to fail, so I don't have much to compare against.

If it is the pump, I have a new one ready to go in. Quickly spinning the new pump, it's basically silent, although spinning it with my fingers hardly gets it up to the revolutions per minute it would be running at while it's on the engine, so I'm not basing my entire diagnosis on this. I could install the new pump and see, but it would be a waste to remove the upper and lower hoses and secondary coolant lines, destroy the old O-ring and drain out the fresh coolant only to find there was nothing wrong with the old pump to begin with.

Any thoughts?

Tried the stethoscope trick?

Simple way is to loosen the adjusting screws around the waterpump and remove the belt and start the motor when cold and see if the noise is absent.Good idea to tighten the bolts a bit as well as the cover may seep water/coolant.Safe to run the motor for a couple of minutes so don't worry!!
If it is quiet "Bingo" its the waterpump. Vee

Tried the stethoscope trick?

Can't say I have. I would ask what it involves but I think for the most part it explains itself.

I suppose I could loosen the water pump bolts, rotate the pump up slightly and run it without the belt attached for a couple of minutes on a cold morning. The only problem I can maybe see occurring is that the twisting of the pump would break the O-ring seal where the pump enters the block and I'd be back at square one anyway, needing to replace the seal and/or pump, the hoses, refill and then bleed the system. Of course I could be wrong and some gentle movement is entirely harmless. I still have a few things to learn here.

When I used to work at mits 90% of water pumps on the 2.6 when touch would break the neck off. Best way to check it would be to remove the pulley off the back of the cam. Place a screw drive between the rocket cover and lift point by memory so when you undo the back bolt for the cover, you don't snap it off the rocket cover.

A new water pump is like $45 on eBay, $120 in shops

When I used to work at mits 90% of water pumps on the 2.6 when touch would break the neck off. Best way to check it would be to remove the pulley off the back of the cam. Place a screw drive between the rocket cover and lift point by memory so when you undo the back bolt for the cover, you don't snap it off the rocket cover.

This is what I was thinking. If the neck were to snap, I suppose it would reaffirm that the pump was worn out and required replacement anyway, but if I don't have to break it then I'll leave it. Is it difficult to remove the pulley from the cam? If I recall it's a single bolt, perhaps holding the pulley in the process to prevent the cam from turning. Anything else I should know or is it that simple?


A new water pump is like $45 on eBay, $120 in shops

Already have a low kilometer water pump that I saved off my old TR. May need to renew the O-ring, but the pump itself isn't very old and is still in fairly decent shape.

Very easy shouldn't have to hold the pulley, just give the ratchet a hit with your hand. You may need to pry the pulley off with a screwdriver.

Good to know, sound advice makes it all the easier. Thanks. :)

Took the opportunity today to clean up and inspect the replacement pump. It doesn't look too bad, the coolant channels are fairly clean and the impeller is in great shape. There's no play in the bearings and it spins freely with no noise, always a positive sign. Since I'm working to a strict budget of almost nil, I gave it a clean with a wire brush to remove any light corrosion on the fittings then flushed it through just in case any loose particles fell inside.

The O-ring looks to be in pretty decent shape actually, probably just as well, so far all I've been able to find are complete pump assemblies with the O-ring and gasket. I'd still like to replace it if I can, but some of the places I've asked haven't been the most helpful just yet.

http://i44.tinypic.com/ettr9u.jpg
http://i42.tinypic.com/9kcw75.jpg
http://i41.tinypic.com/2ymvt52.jpg
http://i40.tinypic.com/30jquiw.jpg

Also something I found is that the old pump looks fairly tired. Not broken or leaking, but the odd rusted bolt head or two on the pump itself and the casting itself looks a bit on the dirty side. I wouldn't be surprised if it's been on there for quite some time and is coming up on being due for replacement anyway.

Have you tired mitsubishi for the seal? Can't remember if they sell them seperate or not.

Any good seal/bearing place will be able to match up the "O" ring for you. The replacement pump looks pretty good on the outside as very little corrosion on the hose inlets etc!!
Pretty sure its the pump as not much else high up that end of the motor that will make that sort of noise. Vee

i get the O rings from bursons

the 'O' ring is a standard 4 mm section with OD of 33.5 mm. Just get one from a bearing shop.
Usually they only stock imperial sizes, but i was lucky and got one that had been ordered as a larger batch.
Remember always, car makers dont make bearings or seals or heaps of other stuff so its usually the case that this stuff can be had.
Also, remember to clean the inside of the bore where the 'O' ring seals against the block. Use a fine grit paper and clean it smooth.
rumpfy