Thread: Td5 Overheating - your thoughts...

Originally Posted by onebob

a sloppy reply on my part which with only just a little more effort I could have explained it more fully, mea culpa; I’ll correct the record.

Yes the o ring is circular, its profile is one that it has two flat surfaces and two ridged surfaces. The flat surfaces are the the inner and the outer circumferences of the o ring and allow for it to fit snuggly into the straight sided circular slot provided for it in the accessory bracket. The ridged surfaces allow for a compression seal when the accessory bracket is bolted to the engine block.

An old o ring will come out square looking because the compression surfaces have been “squished” flat overtime..

Definitely one of those times when the expression " remove the O ring and discard it" needs to be taken seriously. Unless doing things twice floats your boat.

Originally Posted by Graeme

I wouldn't expect to see any wear on the steel impellor blades and the splined press fitted impellor looks fine to me. However in what condition are the other dogs and does the old pump's shaft spin freely?

I've had your comment in the back of my mind constantly. I thought it was ok, thinking it was a female dog. I cleaned out the area, and it is a spot thats very hard to see as the turbo is in the way and the phone photos didn't confirm for me anything other than it looks normal. I put the new pump in (genuine) and there seemed to be an excessive amount of lash. I removed, cleaned again, rechecked and the second time I realised the dogs were only barely meshing. Pump out again.

Had a check on RAVE (no help) and online at D2 Td5 PAS pumps to see what the dogs should look like. You're on the money Graeme, farmers experience! The dogs on the back of the PAS pump are gone as well. <forehead slap>

I'm guessing I'm up for a new PAS pump too.

Here you can see the old genuine water pump vs the new genuine water pump. Dog gears are broken off the pump.



This is the back of the PAS pump that the water pump drives off. I thought the drive was like a female dog gear as the surfaces looked smooth and complete. However the gear meshing was very very marginal and there was a lot of lash which inspired me to check against RAVE and internet pics



This pic of the PAS pump (pic from KLR in Windsor) shows that the dog gear on the back of that is in fact male, and they have snapped or machined off with my PAS pump which is also causing a lack of pump drive.



Interestingly, when I cleaned out the area between the PAS and water pumps, there was no evidence of the dog gears, I'm guessing they got pounded into the black powder that was in there.

Far out! That's a new one for me!

Originally Posted by shack

Far out! That's a new one for me!

Me too!

You'd have probably investigated the backlash anyway but perhaps the prompt helped.

Many years ago I took a RRC front tailshaft to have a new spline fitted but it was pointed out that the inside spline of the other part of the shaft would also be worn just as much. A few months ago I had my L322's transfer case removed to have the gearbox o/p shaft and TC input shaft splines greased to prevent both having to be replaced in another 150K kms.

Job done... and redone. I'm pretty slick at changing lots of things on the Td5 these days, it's getting a bit like grandpas axe!

I removed the pump through the back

Remove coolant
Remove all induction between Airbox, turbo, intercooler.
Remove airbox
Remove Full flow
Remove Centrifuge housing as one complete unit
Remove fan, shrouds and belt
Remove upper radiator hose
Dismount AC pump put to the side
Remove Water Pump cover.
Remove water pump.

Found the dog gears on the water pump and the back of the power steering pump were destroyed. Now to come in through the front.

Dismount ACE pump put to the side
Remove PAS pump pully
Disconnect PAS pump lines, catch fluid for discarding
Removed accessories mount with Water pump and PAS pump in situ.
Remove PAS pump
Clean accessories mount of all deposits and build ups.
Install new genuine Water Pump (old cover used as it was perfect, however replacements are recommended due to erosion)
Install new PAS pump (Genuine not available)
Install new O ring
Reinstall Centrifuge housing
Reinstall full flow
Reinstall accessories mount
Reinstall hoses, electrics, induction system
Refill with Coolant, burp it, PAS fluid

Test drive - AC is cold! Coolant leak I suspect from O ring between block and accessories mount.

Remove fan, shrouds, drive belt, airbox, induction hoses.
Remove coolant and upper radiator hose
Dismount AC, PAS, ACE pumps and put to side.
Remove accessories mount which contains water pump only.
Clean the life out of the accessories mount and the side of the engine block
Remove O ring and reinstall O ring - see notes re O ring installation.

Reinstall everything again, refill with coolant and burp it.

Test drive - bonza, the ol' jalopy is now back in action.


The O ring installation!
That O ring is not a normal O ring and gets installed differently.
The O ring has a ridge on the top and bottom of the ring, and it also has a run that runs around the outside.
Don't push the O ring into the groove on the accessories mount, it will leak so it seems. Sit the O ring on the groove so the step catches on the groove.
The reinstall the accessories mount. This way, for whatever reason (maybe it pinches the O ring to generate the seal) it will seal and not leak.


If I had my time again, to change the water pump I would not follow RAVE. Instead:

Remove Coolant
Remove airbox and induction lines
Remove fan, shrouds and belt and upper radiator hose
Remove PAS pump pully
Dismount PAS, AC and ACE pumps and put to side - don't disconnect any lines.
Disconnect water pump hose
Pull the accessories mount.
Clean accessories mount and engine block
Replace pump cover and pump on the bench
Inspect PAS pump dog gears for wear
Replace O ring
Reinstall everything.
Refill with coolant and burp
Test drive

Hot tool tip. To do it this way you will need a 13mm 1/4" drive socket and 2x 150mm extensions to R&R the rear centre bolt on the accessories mount as the pump cover restricts access. Everything else are just standard ratchet ring, open ended, and 1/4 + 1/2" drive sockets, pliers, screwdrivers and multigrips.

Wow, I've never heard of that sort of failure either!

And yes, it's a PITA to do the water pump, housing O ring, etc. JC tipped me off to the speciality nature of that O ring.

I did it as per RAVE too, and I was only doing the water pump as a JIC as the car was 18 years old at the time. I ended up doing the rad, hoses, t/stat, etc. too.
Glad you've sorted it.

Originally Posted by rick130

Wow, I've never heard of that sort of failure either!

And yes, it's a PITA to do the water pump, housing O ring, etc. JC tipped me off to the speciality nature of that O ring.

I did it as per RAVE too, and I was only doing the water pump as a JIC as the car was 18 years old at the time. I ended up doing the rad, hoses, t/stat, etc. too.
Glad you've sorted it.

I'd never seen an O ring like that before. It wasn't until afterwards, when it was leaking, that it dawned on me why the O ring was like it was. Interestingly, the centrifuge housing which is a similar application is a normal style O ring. IDK.