lpg conversion problem

[tony mcscaff]

cylinder head valves

[qapmoc]

in the cylinder head

[v64paul]

usually. but if the lpg conversion is botched, they'll be found in the top of the pistons...

[tony mcscaff]

never fully gave the full picture here goes:
my nissan primera 2litre automatic 02 reg has had big problems lately stalling often etc advised me to look at the compression the cylider head was taken off by nissan and showed that the valves needed replacing or skimming took it to a independant repairer who now is doing it, the car has only done 28,000 miles and was converted to lpg 18 months ago at 10,000 miles .However the cause seems to be the heat from the gas entering the chamber is washing off any lubrication on the valves so the valves now are knackered even at 28,000 miles .I have been in touch with a local lpg installer and he said there is a vapouriser(dont know if its called this excise my ignorance) or some device that can inject into the cylinder head a lubricant so reducing the friction and keeping the valves cooler and lubricated, can you please let me know if you have any info or advice about what I should do next when the cylinder head is restored to my car ,I am going to stay on petrol (unwillingly) till I know that what is done is not going to repeat itself and cost me another fortune to put right part 1 of post

[tony mcscaff]

part 2 of post:.The Nissan home site as said as from march 2005 they will not supply vehicles specifically for the purpose of being converted to run on lpg and therefore will not take any responsibility for any warranty(is there something quirky about converting a primera to lpg as the mechanic doing the cylinder head said he hardly ever gets heads from any nissan cars but thats ones running on petrol) I am going to put this on the forum to gather as much info not only for myself but others to re act too. Long post SORRY should have been advised by installer that car needs Flash lube fitted. As I understand alot of the latest cars have to have this fitted to prevent Valve seat recession and accosiated problems. Similar problem to when 4star fuel was phased out, older cars had to have a lubrcant added to the unleaded petrol to prevent this happening.thanks

[qapmoc]

Hi Tony, yes you do have a problem, apparently Nissan Primera is one of the cars mentioned which has trouble with valves after LPG conversion, You had better ask the repairer to see if it is possible to obtain/fit extra hard valves/seats to the head. And it would seem that you should have the Flashlub or equivalent system fitted to almost any vehicle which was not manufactered to run on LPG but has been converted after.

[stanleyman]

I'd change it for a diesel, a lot less trouble and more economical.

[lebesset]

tony , cylinder head valve seats [primarily exhaust ] vary dramatically in quality ; unleaded petrol doesn't have any real lubrication , so certain cars are poor on valve seat recession even then ,ford , honda and nissan for example
not sure how much flashlube adds to your running costs , but it seems to help somewhat

but your simple solution with the head off is to have properly hardened seats fitted ...and your problem is gone ; forget flashlube ;I used to run volvo's which have proper hardened seats [ always did] ; at 150K on lpg had the head off the last one .....valve seat recession zero ; the identical engine used in a renault with a renault head , quite the opposite
I take it you have fully appraised the engineering shop of how this has come about ....quality hard inserts are easily [but not cheaply !] available , presumably for this engine as well !

[tony mcscaff]

I would like if possible to get in touch with lessebet with an e-mail his answer seems the best course if action for me and I would like to know further any info from him I have tried the plgforum site which he has gave me in the past to see if he is there but no luck certainly not under lessebet