Seized strainer cap

[kalanka]

The plastic cap on raw water strainer. on my Volvo 2003 has seized. It has an O ring and screws into the strainer bowl. I only ever hand tighten, with a smear of silicone grease. Unfortunately, the cap only has four teeth which are a very loose fit to the supplied nylon spanner. I have tried hot water and detergent spray but am nervous about using release oil or other solvents in case I glue the whole thing even worse. I can apply fair force with a filter wrench and there is no sign of movement at all. Any ideas? Thanks

 

[johnalison]

I can’t believe that releasing oil will do anything worse than damage the O ring. It might not work, but worth a try. Some threads will free if you tighten a bit first but I’m not sure that this applies here.

 

[penfold]

Are those crazing lines on the cap? If they are it's time for a new cap or a new strainer. Crazed acrylic windows annoy, but this is keeping the oggin out. Sprays are no use with plastic, pour boiling water over it. Bit dubious if you can't shift it with a filter wrench, are you sure you're turning it the right way?

 

[vyv_cox]

Well worth making a wrench for it from plywood. They do tend to stick on after a while.

 

[Daydream believer]

Wind a sail tie around the cap tightly about 3 times, anti clock wise. Then place a piece of wood about 3/8 * 1 inch * 8 inches, under the tail & continue to wind a little so the end becomes trapped with the long side in line with the tail. grip tail & sail tie tight to prevent slippage & continue turning. The wood will bear down on the turns of the sail tie on the cap causing it to grip the cap. The sail tie wil apply even pressure over the cap rather than in a point so less chance of cracking it.
If one wants to pre heat the cap, do not just pour boiling water on it. Wrap the cap in a tea towel & soak the towel in boiling water, so that the heat is retained longer around the cap.

 

[LittleSister]

. . . I have tried hot water . . .

Any ideas? Thanks

I'm afraid you need to apply some more persistence!

The thread on the cap is external, it seems, so you need to be heating the fitting/strainer bowl, not the cap, and keep the cap cool. Maybe that's what you've been doing, but keep at it.

It will be difficult to apply sufficient heat to the strainer body with just hot water externally unless you have a good supply of it, and can make some arrangement to maintain the water against the body rather than it just run straight off. You can try wrapping it with a bit of rag/towel, and pour the water into that, but keep squeezing out the rapidly cooling water and apply fresh hot to the rag.

If the boat is out of the water you could fill the strainer with hot water: open the seacock to drain the strainer, close the seacock, take the supply hose coming out of the filter off at it's opposite (water pump) end, put a small funnel in it, and pour almost boiling water into that.

While heating the body, keep the liid cool by putting some cold water, and ideally ice cubes, in the 'dish' of the lid.

Good luck!

 

[ctva]

Have you tried an oil filter wrench, I have one that is plastic with a rubber strap and works well if you have the turning room, otherwise the three legged filter wrench with a spanner?

Edit: Mr P below shows what I mean.

 

[Poignard]

 

[thinwater]

Are those crazing lines on the cap? If they are it's time for a new cap or a new strainer. Crazed acrylic windows annoy, but this is keeping the oggin out. Sprays are no use with plastic, pour boiling water over it. Bit dubious if you can't shift it with a filter wrench, are you sure you're turning it the right way?

Give this guy the gold star. I think that is crazing.

If that is the case, the solution is simple. Loosen the hose clamps and replace. It's not worth loosing water and overheating/ruining the engine. Obviously.

Has the engine been winterized with polypropylene glycol or alcohol? If yes, that is the cause. Instead, use ethylene glycol, which will not damamge the plastic. The toxicity to marine life is the same (Google the two SDSs if you don't believe this).

EG vs. PG. Plastic compatibility and marine life.