Bigas vapouriser overhaul

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cljcars

Active Member
Posts
327
Right, started this little job because the bottom joints,o-rings where leaking coolant showing a very slow loss of coolant level in the expansion tank on my 4.6 p38. I only noticed this because i lifted the bonnet to top up after a coolant change. Damp patches around the base and wet underneath the vapourisers.

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I tried, after some advice from lpg specialist, to tighten the 5 scews around the base to no avail.

So i ordered a kit. these are vary early RI-20 bigas vapourisers or reducers. The kits for the new ones fit.

Remove the Gas from the system! No first thing to do is, Disconnect one of the cables from your shutoff valve. switch it to gas and wait for it to switch back to petrol. This empties the gas from the shutoff valve to the injectors. LPG chap told me to do this (Work well only a slight smell). Photo of valve, pull one of the cables off.

Then pull all the gas hoses off first, once I had done this I lifted the vapourisers higher than the expansion tank so i didnt loose to much coolant (just changed it didnt want to loose it).

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Then, once you have it high out the way, look on the back of the vapouriser, there are little grub screws holding the coolant feed/return in. loosen them off to get them out, dont loose them.

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Strip down, bottom off first.

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How dirty can you get, the seals where completely perished, almost as bad as the matrix seals done last week.

Clean out all the carbon and replace the seals, making sure all the valves and springs go back in the same place.

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Thats the strip down, put it back together the same way it came apart with all the new seals, the gas side o-rings are a different material, improoved chemical resistance to the gas. I think I was not far of the gas entering the coolant through the vapouriser. The seals inside where terribly perished.
Don't mess with the regulator setting unless you want to take it straight to the LPG chaps, I will be buying one of those bigas cable thingys next week to check all the settings are ok. When I started and ran the Rangie on gas there was no noticible differance in performance from before I serviced them. I was expecting an improvement after finding all the carbon in them both, didn't happen.

If nothing else it give people the idea of whats inside the vapourisers, I couldn't find a drawing anywhere.

Don't forget to change the o-rings on the coolant inlet/outlets.
 
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