Hi All, has anyone succeeded in replacing this cap at the front of the engine without destroying the plastic threads on the pipe? I don't want to attempt it if it's less than a 50/50 bet. I don't mind replacing the cap if it's easy to get off but I have seen other posts where the complete assembly ends up being replaced due to the plastic shattering and as I don't have a place to work on it that would have to be done at a shop.

So there is an obvious small leak because there is all the staining around the cap and post but here's the thing, the allen key slot actually fills up with water so maybe it's just the crossover hose? It is a bit bloated so maybe I should just replace that first without touching the cap?

is there a trick to removing the cap without breaking the plastic pipe? Do you actually use a giant allen key to remove it or would something like an oil filter belt type remover work better? Should it be sprayed with any kind of thread cleaner first?
Thanks
Alan

 

I had the very same leak coming from the allan key socket,to remove and replace mine I used mole grips set just at the right grip not to tight worked great for me,having said that 3months later I replaced the full thermostat tower with alloy fitment but my new plastic cap in them three months had no signs of a leaking

 

I suspect the majority here would suggest changing the complete plastic "tower" assembly with an aluminium (aloooominum) unit. Not expensive and completely solves a known issue.

https://www.sngbarratt.com/uk/#!/Eng...7-5f79d06d8d2c

 

Thanks Graham, did you use anything on the threads (spray) to make it easier?

 

No mate to take off I didn't as I could not get at the threads just a bit of wd40 before I replaced it

 

After my indie suggested about $900 to replace the "tower" with the aluminum version I decided to try a cap and gasket only replacement. I had seen pics of how badly the plastic tower can corrode and the threads disintegrate so I was very gingerly easing the cap off. To my delight the plastic/threads etc on the tower look to be excellent with no corrosion so I have ordered a new cap and will see if that does the job. Hopefully then the little Allen key slot will no longer fill up with coolant. Couldn't see any obvious cracking in the old cap though so I hope that's all it is.

 

I was very lucky! Plastic tower was in excellent condition. Replaced just new cap and no leaks so far. Looks to have been that the rubber seal parted from the cap.
With the new one the rubber seal is held in place behind a plastic lip but it was loose and no longer behind the lip on the old one I removed.

 

You need to consider a new mechanic. It takes me about one hour to replace the tower and connecting hose. Be aware that the outlet pipe just below the tower is made of the same plastic.

 

Now that the cap is replaced I would like to clean off the old coolant stains on the plastic tower. I cant really get a rag in there without removing parts and I don't have anywhere to work on the car. Can anyone recommend a cleaning spray that would work without eating the plastic or the rubber hoses?

 

Alan, since it's water soluble to start with, how does a hose with a sprayer nozel on the end work?

Dont forget to buy a gallon or 2 of distilled water. Use that as the final rinse pour over to ensure no mineral spots.

John

 

The hose idea is going to cause wet knock sensors, I don't think I would do that.

 

^^ Agreed. I clean the Jaguar engine bay using only old rags, a bit of silicone spray, and plenty of elbow grease. I never use any water at all in that area....