Who moderates this section of the forum?

I have just bought a ZJ Cherokee... Do I need to cuddle that???

https://farm2.staticflickr.com/1854/...c750d69f_h.jpg

Head gasket first... Cuddles later.

You will, yes. That said that looks a bit later and i don't know if they moved it - doubtful as it had been there for a long time!

What year is it and what makes you think the head gasket has gone? Some years had a problem with the head and were prone to HGF but most were near enough unburstable. ;) :D

Pressure in the coolant pipes when cold.
K-Seal (copper flakes) in the coolant already (previous dealer/owner's attempt at a "fix"), and the inevitable leaks in the coolant system due to the pressure.

It is a gas converted 1998 Grand Cherokee Orvis. I wasn't going to get one without gas conversion, as the price of petrol is so high.

It still has a distributor. I would like to convert it to COP ignition, when funds permit. I have joined the Jeep owners club, as I knew I was going to need lots of advice!

From memory that's too early to have one of the "troublesome" heads so once done you should be ok. Unusual for them to go though and i suspect probably down to a vapour lock in the cooling system possibly because of the LPG install that has two rookie mistakes that i can see from your pic straightaway.

First, follow the top hose (feed to the heater matrix) from the water pump end to the T then follow the t leg where it feeds the reducer - it goes into the bottom! :err: :nah:

Should go into the top and out the bottom or it's constantly fighting its own weight to get through.

I had exactly the same problem on mine which leads me nicely onto the second rookie mistake - the reducer is too high so it will never bleed properly - it's higher than the highest point in the cooling system. I also had this problem and it led to vapuoriser icing, even on idle on a hot sunny day!
Many of the people on the LPG Forum refused to believe i had vapouriser icing until i showed the photos at idle!

As for the dizzy cap, rotor arm and HT leads, they're a service item at 30k if memory serves - reasonably cheap as well so no excuse for not doing them!

A couple of useful links for you :

http://www.birtydastards.com/frm/

That was the only UK based Jeep Forum i found - maybe more that i didn't find but they're a helpful bunch.

http://gojeep.willyshotrod.com/

Second one is well worth a read in its entirity including the bit about fitting a restrictor in the thermostat outlet (11m hole through a washer blanking the rest of the outlet) to help prevent overheating and HGF - sounds counter-intuitive but it works and improves heater output as well which also mean it will improve the water temperature round the reducer leading to better LPG vapourisation. ;) :D

Wow, thanks for the heads up on that, pun intended!

Have you also noticed on the 4th and 5th cylinder injector pipes are crossed over, I will check the wiring diagrams to see of the plugs are also crossed. I spotted that today when removing the fuel rails.

Looks like I should get the whole system checked after fixing these obvious issues.

I may end up PMing you as I start to put it back, to check things are ok.

I did notice that but unless my memory is totally to pot, the Jeep uses Full-Group aka Batch-Fire injection so it won't make any difference. I'd have to exhume my Cherokee HBoF to double check. Do you know what sort of system it's running? I can't see the LPG ECU but if it's something like a King, Zavoli, Romano or similar, you just need the right lead and software (freely downloadable or i might be able to email you a copy) and an old laptop with an RS-232 socket and preferably running XP - for some reason XP seems to be the latest that usually has an RS-232 port and also seems more stable running the RS-232 link. Yes, it's a more reliable connection than USB for this. ;) :tounge_smile:

Feel free to PM me about it, i'll do what i can to help. ;) :D

Ah, so not fully sequential then?
I did wonder about that.
It's an LPG-Tech ECU, it is a metal one that looks like a 326 (not sure if it is OBDII or not), I will have to have a look tonight.

Cheers

Just a thought, does it batch fire 1-2-3 together then 4-5-6 ?
Or is it in 3 pairs?

Having double-checked, my HBoF doesn't contain the wiring diagrams for the PCM (Powertrain Control Module aka ECU) but i did manage to find some diagrams online, all of which point to it being fully sequential :

https://www.cherokeeforum.com/attach...ctorwiring.jpg

However mine was a 1994 and i know when i had a broken wire inside #6 injector plug, swapping with #5 shifted the fault and it ran perfectly when i linked them. That said, it's a few years ago now and i can't remember if it was the +ve feed to the injectors which is common or the earth which is switched through the PCM. Either way it gave me the idea it was batch-fired, apologies for misleading you!

Back to the LPG injectors, there's a fair chance they hard-wired the LPG and inadvertently swapped the wiring round then soldered it. As such they probably swapped the gas pipes from the injectors to compensate. Until you get it running and proved it runs fine on all 6 on petrol, i wouldn't worry too much about the gas side of things.

As for LPG-Tech, they seem to be reliable bits of kit and sell the leads and (i think you can get the software free but don't quote me) software on their site.

http://lpgtech.eu/

There is another site that sells LPG-Tech in the UK, think it's :

http://lpggpl.com/

Not being funny but rather than thread-jacking this thread, would you like to take this to PM? ;) :D