Thermostat O-rings

chicochapman · 15th April 2024, 10:32

Well, if ever this weather lets up, I'm going to have to change the O-rings as I have coolant in the "V". Although I fitted a new thermostat a couple of years ago, I can't remember whether I can change the O-rings without removing the thermostat, as I do remember it was a tricky job!
Can anyone advise me please?

Thanks,
Malc

Matt_75 · 15th April 2024, 10:45

Hi Malc,

Yes, you'll need to remove the thermostat, straight and curved plastic pipes to replace the four o-rings (CDU3858).

Whilst it's a bit more work, I'd recommend removing the plastic intake and front (left) inlet manifold. With them removed you have much better access to clean the mating faces in the engine block (with some Scotchbrite or similar) that the o-rings sit in and you can be confident that it's all properly seated. You will need a new manifold gasket (LKJ100992) though.

Hope this helps.

chicochapman · 15th April 2024, 10:57

Thanks very much Matt. I can see from your excellent photograph that the access is vastly improved! Thanks for the part No. refs as well.
Malc

SD1too · 15th April 2024, 11:32

And Malcolm, after reassembly make sure that you push the serrated clips on the straight pipe fully outwards to be in close contact with the water pump boss and thermostat housing, then squeeze them tight.

I'd recommend ordering two new clips (along with the O rings) to make the job easier. The part no. is PYC 101320.

Simon

Rich in Vancouver · 15th April 2024, 18:59

And, if you have one or both parts of the intake manifold off don't forget to order new manifold gaskets.

Sonestarick · 15th April 2024, 19:20

Hi Malc,
Interested in how the job panned out regards replacing the "O" rings on the straight pipe and fitting the serrated clips flush up to the water pump at the one end and the thermostat housing at the other end thinking that surely would eliminate any seepage of coolant into the V.
Very interested to know how it all went and that you cured the problem.
Cheers
Rick'

chicochapman · 15th April 2024, 21:30

Thanks everyone for your help and advice. I'll be sure to let you know how I get on as soon as we have a couple of dry days - when ever that might be!

Cheers,
Malc

15th April 2024, 10:32	#1
chicochapman Avid contributor MG ZT-T Join Date: Feb 2019 Location: Stockport Posts: 135 Thanks: 56 Thanked 22 Times in 20 Posts	Thermostat O-rings Well, if ever this weather lets up, I'm going to have to change the O-rings as I have coolant in the "V". Although I fitted a new thermostat a couple of years ago, I can't remember whether I can change the O-rings without removing the thermostat, as I do remember it was a tricky job! Can anyone advise me please? Thanks, Malc

15th April 2024, 10:45	#2
Matt_75 Gets stuck in 75 Saloon Join Date: Apr 2022 Location: North Somerset Posts: 549 Thanks: 13 Thanked 20 Times in 8 Posts	Hi Malc, Yes, you'll need to remove the thermostat, straight and curved plastic pipes to replace the four o-rings (CDU3858). Whilst it's a bit more work, I'd recommend removing the plastic intake and front (left) inlet manifold. With them removed you have much better access to clean the mating faces in the engine block (with some Scotchbrite or similar) that the o-rings sit in and you can be confident that it's all properly seated. You will need a new manifold gasket (LKJ100992) though. Hope this helps. __________________ Matt 2001 Rover 75 Connoisseur SE 2.5 (BRG) 1999 Rover 75 Club 2.5 (Dorchester Red) 1973 Triumph Dolomite (Honeysuckle)

15th April 2024, 11:32	#4
SD1too Doesn't do things by halves Rover 75 2.5 Connoisseur Auto (1999) Dealer launch model. Join Date: Mar 2007 Location: Former Middlesex Posts: 20,395 Thanks: 1,587 Thanked 3,749 Times in 3,181 Posts	And Malcolm, after reassembly make sure that you push the serrated clips on the straight pipe fully outwards to be in close contact with the water pump boss and thermostat housing, then squeeze them tight. I'd recommend ordering two new clips (along with the O rings) to make the job easier. The part no. is PYC 101320. Simon __________________ "Whatever is rightly done, however humble, is noble." Sir Henry Royce.

15th April 2024, 18:59	#5
Rich in Vancouver Gets stuck in MG ZT-T Join Date: Jun 2016 Location: White Rock, BC on Canada's Pacific Coast Posts: 851 Thanks: 338 Thanked 367 Times in 210 Posts	And, if you have one or both parts of the intake manifold off don't forget to order new manifold gaskets. __________________ ZT-T190, Anthracite, LHD, Left the Line on June 24, 2002, Sold new in Switzerland, spent time in Germany, Imported to Canada in September 2021

15th April 2024, 19:20	#6
Sonestarick Regular poster Rover 75 Saloon Join Date: Apr 2016 Location: Folkestone Posts: 35 Thanks: 0 Thanked 0 Times in 0 Posts	Cooant in the " V " Hi Malc, Interested in how the job panned out regards replacing the "O" rings on the straight pipe and fitting the serrated clips flush up to the water pump at the one end and the thermostat housing at the other end thinking that surely would eliminate any seepage of coolant into the V. Very interested to know how it all went and that you cured the problem. Cheers Rick'

15th April 2024, 10:57	#3
chicochapman Avid contributor MG ZT-T Join Date: Feb 2019 Location: Stockport Posts: 135 Thanks: 56 Thanked 22 Times in 20 Posts	Thanks very much Matt. I can see from your excellent photograph that the access is vastly improved! Thanks for the part No. refs as well. Malc

15th April 2024, 21:30	#7
chicochapman Avid contributor MG ZT-T Join Date: Feb 2019 Location: Stockport Posts: 135 Thanks: 56 Thanked 22 Times in 20 Posts	Thanks everyone for your help and advice. I'll be sure to let you know how I get on as soon as we have a couple of dry days - when ever that might be! Cheers, Malc