Note : Change to Aisin branded water pumps

Post by **scot850** » 31 May 2023, 19:38

I am replacing the water pump on a friends 96 850 base 10V engine. I now recall why I stopped doing them and paid others to do it for me!!

I got my friend to order a replacement Aisin water pump as it is the OE supplier. Pulled it out the box today to find not only is it different to the aftermarket one fitted to the car, but also an older Volvo pump I pulled as a spare from a low mileage car.

I had planned to re-use a set of Volvo pump bolts from the used Volvo pump, but realized they were about 5mm longer than the bolts I took out with the aftermarket pump.

: Water pump bolt size change; PXL_20230531_220603063.jpg (577.39 KiB) Viewed 1091 times

The Volvo bolts from an older pump are on the right and those from the aftermarket bolts are on the left. The shorter ones are 25mm and the Volvo OE are 30mm from the old pump.

The 2nd issue is the bolt stanchions for the old OE pump and the aftermarket pump are 4-5mm thicker than the new Aisin pump. The difference is on the top side of the pump

: Pump thickness change; PXL_20230531_221149695.jpg (311.54 KiB) Viewed 1091 times

: Original Volvo OE pump; PXL_20230531_225751570.jpg (283.23 KiB) Viewed 1091 times

And this is the new Aisin pump:

: New Aisin pump; PXL_20230531_225702649.jpg (270 KiB) Viewed 1091 times

The good news is the pulley is still in the same place and the same distance from the face of the pump.

I have just realized looking at the photo above there may be an even larger discrepancy on the bolt furthest to the Right on the new Aisin pump.

So I decided to check the depth of the holes in the block. I discovered that at least one bottoms out, 2 are deeper but feel like they bottom out, and the other 4 go all the way through. I thought this may be ok, until I discovered the bolt holes do not appear to be threaded all the way through. I estimate they are threaded to maybe 15mm but I will depth check all the holes tomorrow with a bolt and nut so I can measure the threaded length.

So I have the choice of waiting for a few days to order a set of bolts from Volvo Vancouver at $3.33 each, or the local dealer ho has taken to charging over the MSRP on parts which is $6 in this case, but not sure what they actually are charging. That would make the bolts about half the price of the pump!! I could have bought a Volvo pump which I understand come with the bolts for about $165 from Volvo of Vancouver but have to wait again for delivery.

My only other choice is to clean the aftermarket bolts, and use some Permatex with PTFE. Naturally no one in Calgary has it so have to wait to get it from Amazon which hopefully will get here tomorrow as I am now stuck moving on.

I will add to this thread tomorrow when I measure the bolt holes for depth.

I should add that I looked at pictures on Volvo supplier sites and the pictures seem to show this new 'thinner' bolt stanchion pump.

So watch what bolts you use if you reuse them!!

Neil.

454cid · Post by **454cid** » 31 May 2023, 19:52

Interesting. My Aisin pump was identical the the original. You could even see that the new pump had the "Volvo" name ground off.

Post by **scot850** » 31 May 2023, 19:57

It may depend on stocks of the pumps in different locations. It should all work but a typical pain that I always seem to find.....!

Neil.

Post by **abscate** » 01 Jun 2023, 03:25

Option (iii)

Lop off 5mm from the new bolt with a Dremel and press on. Spin an M6 nut on it first to chase the threads

Are you going to nicely map the 7 water pump holes for us so we can archive the depth and through hole nature of the fitment?

Post by **scot850** » 01 Jun 2023, 08:37

Yes I am!

I had thought about cutting the bolts, and I do the nut on first thing since my grandfather showed me about 50+ years ago! However, the aftermarket pump that has failed has bolts the correct length I think. I have bought some liquid thread sealer which should be here today.

I think we are on the last drop off point for Amazon so maybe by end of day?

I'm spending some time today mapping the bolt holes, and then giving the car a once over. I already see a possibly bad crank pulley mount, a LH outer tie-rod boot, possibly end of life main coolant hoses to name a few. There are also some trim stuff to investigate as well as that trunk lock.

Neil.

Post by **scot850** » 01 Jun 2023, 19:40

As I have been waiting all day for the delivery of the thread sealant from Amazon (I'm sure we are the last drop off for packages.....!), I took time today to measure the bolt hole depths and came to a surprising discovery.

I don't know how to annotate a picture, but I'll try to figure it out. The 5 bolt holes closest to the left are all through to fresh air!! The bolt limits are either because the threads were not turned all the way through or they are full of crap from being open for 27 years.

The 2 most RIGHT. (2nd from top Right and 3rd from top) are not drilled all the way through. They have a max. depth of 22mm approx.

Good news is the original bolts on the car with the aftermarket pump will work. At 25mm long (which is I believe the length of the current Volvo bolts) it gives about 3-4mm space in all the holes with the thickness of the pump and the gasket. The old bolts are 30mm and would bottom out (just) in the holes.

Not sure what the thread sealer is for? Thinking about it, either Volvo has a problem with the pump gasket not pulling flat, or the gasket becomes porous with age allowing coolant to get to the bolt threads and leak along them. The gasket should surround the bolts completely so how does the water get to the threads??

Neil.

454cid · Post by **454cid** » 01 Jun 2023, 19:54

scot850 wrote: ↑01 Jun 2023, 19:40
Not sure what the thread sealer is for? Thinking about it, either Volvo has a problem with the pump gasket not pulling flat, or the gasket becomes porous with age allowing coolant to get to the bolt threads and leak along them. The gasket should surround the bolts completely so how does the water get to the threads??

Neil.

I dont believe I used a sealer. I mentioned i think i used Loctite, although I may have used anti-sieze.

Let me back up...when I say Loctite, I'm speaking of blue thread locker, (232, i think) not one of thier other products

Post by **scot850** » 01 Jun 2023, 22:53

I had considered that as an option. What I had been reading gave the impression the thread compound was to prevent leaking through the bolt threads and the casing.

Anyway, I now have the thread locker with PTFE which is good at low temps and at over 300C. That will cover the bases!

Thanks for your input. Much appreciated.

Neil.

Post by **wizechatmgr** » 02 Jun 2023, 07:06

Which supplier was it purchased from? I'd send pics to FCP and see if it matches their current stock. I'm rather sure they'd look for you as they don't want to be selling parts that won't work correctly.

Post by **scot850** » 02 Jun 2023, 08:55

It was bought from Rock Auto. Aisin is the manufacturer. I am surprised they did not supply bolts. Even Hepu supply bolts.

Neil.