PabloPicasso
Well-Known Member
I'm refitting a thermostat and related water pipes on a volvo 2001 penta engine. There are O ring gaskets. Should some sort of grease be used to aid the seal and longevity of the o rings?
Grease o rings
- Thread starter PabloPicasso
- Start date
VicS
Well-Known Member
A smear of silicone grease might be a good idea, especially where a little lubrication will help the reassembly. Otherwise where necessary to aid the reassembly saliva or some water based "personal lubricant"
vyv_cox
Well-Known Member
I would expect these rings to be made from EPDM, as heater hose is. The material has poor resistance to hydrocarbons. Unlikely that a bit of grease would cause much trouble but as Vic says silicone should be good. Detergent is also safe and my usual choice.
PabloPicasso
Well-Known Member
Certainly have washing up liquid aboard. Would silicone grease aid the water tightness? I doubt washing up liquid would
Old Harry
Well-Known Member
pvb
Well-Known Member
The O-ring itself is what creates water tightness. Silicone grease or washing-up liquid merely make assembly a bit easier.
Volvo piping tends to use rectangular-section sealing rings. You should be aware that the sizes of these vary according to where they go. The best bet is to look at the parts list for your engine and note down which part numbers go in which places.
prof pat pending
Well-Known Member
Actually the use of a lubricant is there to prolong the life of the O ring, rather than create the seal or aid assembly.
It’s quite important to ensure that you’re not using a silicone O ring if you’re going to use silicone grease, but the vast majority aren’t so it’s probably fine.
It’s quite important to ensure that you’re not using a silicone O ring if you’re going to use silicone grease, but the vast majority aren’t so it’s probably fine.
erich27
Active Member
Hi
If it helps,I worked for some years for a company manufacturing Sights& Periscopes for Armoured Fighting Vehicles and fitted a lot of O rings in that time and all without exception they were fitted with a coating of Dow Corning Molykote 33 grease, which is a high performance silicone/lithium grease.
If it helps,I worked for some years for a company manufacturing Sights& Periscopes for Armoured Fighting Vehicles and fitted a lot of O rings in that time and all without exception they were fitted with a coating of Dow Corning Molykote 33 grease, which is a high performance silicone/lithium grease.
jiris
Well-Known Member
Definitely not anything hydrocarbon based. Silicone grease may be the safest choice. Different materials are being used for O rings and you never know how hydrocarbon resistant your particular ones are. I was using WD40 for years without any problems - until I used it on one of my UW camera. The O ring expanded within seconds and became entirely unusable.
Gentleman of Leisure
Member
I can't see any point in greasing O rings except to make them a bit easier to assemble. I find spittle a good lubricant or washing up liquid for plastic waste plumbing.
vyv_cox
Well-Known Member
An O-ring should seal without any grease being needed. The lubricant can aid assembly, avoiding damage to the ring surface.
vic008
Well-Known Member
What do you call those black seals that Volvo like, and often found sealing thermostats? See someone calling them doughnuts.
VicS
Well-Known Member
Sealing rings
Old Harry
Well-Known Member
The correct answer
VicS
Well-Known Member
pvb
Well-Known Member
Old Harry
Well-Known Member
so is 33And that actually is the correct answer!
prof pat pending
Well-Known Member
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erich27
Active Member
Ah well sounds like we fitted a lot of O rings with the incorrect grease but at least PabloPicasso did get the correct answer ! 
pvb
Well-Known Member
Ah well sounds like we fitted a lot of O rings with the incorrect grease but at least PabloPicasso did get the correct answer !
He did - silicone grease or washing-up liquid.
