P38 Rangie 4.6 pressure in water system

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falconho
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P38 Rangie 4.6 pressure in water system

#1 Post by falconho » Mon Dec 31, 2018 9:22 am

As title says really and it holds the pressure for hours after being shut off, it has been suggested that it could be a split in the vaporizer diaphragm, its a BRC system, I know ive got lots of other things to check just wondering if others have come across this and can you fit a new diaphragm or is it the whole unit Thank you

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Re: P38 Rangie 4.6 pressure in water system

#2 Post by Gilbertd » Mon Dec 31, 2018 9:42 am

It could be an internal leak in the vaporiser just as it could be combustion gasses getting into the cooling system from a leak around the outside of a liner. What sort of mileage does it have on it, a liner on mine was starting to weep after around 250,000 miles? Easiest test is to run it on petrol only, give it a run and see if it still pressurises. If it doesn't, then it is the vaporiser, if it does, it's something else. There's a very helpful, UK based, P38 forum at https://rangerovers.pub for more specialist help.
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Re: P38 Rangie 4.6 pressure in water system

#3 Post by Brian_H » Mon Dec 31, 2018 3:54 pm

If it is the vapouriser that needs an overhaul kit, you can get the bits from TinleyTech who are the uk BRC agent
https://tinleytech.co.uk/product-catego ... and-parts/

It might be worth switching it to gas and either shutting off the outlet on the tank or disconnecting the solenoid from it to depressurise the system then monitoring if the pressure buildup still happens, as there could be a quite a large amount in the front end to seep into the coolant, its only likely to be a slow leak so could remain for quite a few hours like that. Or the front solenoid would work if thats easier to access (just disconnect the plug from the coil, let it cut back to petrol then put it back on, long as its left on petrol operation that should then rule out the lpg being the cause or prove it is where the fault lies).

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Re: P38 Rangie 4.6 pressure in water system

#4 Post by falconho » Mon Dec 31, 2018 10:27 pm

Brian_H wrote:
Mon Dec 31, 2018 3:54 pm
If it is the vapouriser that needs an overhaul kit, you can get the bits from TinleyTech who are the uk BRC agent
https://tinleytech.co.uk/product-catego ... and-parts/

It might be worth switching it to gas and either shutting off the outlet on the tank or disconnecting the solenoid from it to depressurise the system then monitoring if the pressure buildup still happens, as there could be a quite a large amount in the front end to seep into the coolant, its only likely to be a slow leak so could remain for quite a few hours like that. Or the front solenoid would work if thats easier to access (just disconnect the plug from the coil, let it cut back to petrol then put it back on, long as its left on petrol operation that should then rule out the lpg being the cause or prove it is where the fault lies).
I think this is where the problem lies i could not understand why after shutting engine off hours later and engine cool still lots of pressure when undoing Expansion bottle cap, thank you for the link and advice everyone

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Re: P38 Rangie 4.6 pressure in water system

#5 Post by LPGC » Wed Jan 02, 2019 3:24 pm

Agreed with Gilbert and Brian.

I know of several P38 owners who had the same problem (of pressure in cooling system), who went to garages who told them head gaskets were blown but after the garages had fitted new head gaskets the problem remained. Then the owners came to me and I diagnosed their reducers were leaking gas into the cooling system, they'd paid £££s to have the head gaskets done when the real problem was just a faulty LPG reducer (and very unlikely the head gaskets were ever a problem)! Just about an understandable mistake for a garage that doesn't know much about LPG systems to make, but these garages were supposedly LPG installers so an absolutely ridiculous mistake for them to make and very costly for the customers.
falconho wrote:
Mon Dec 31, 2018 10:27 pm
I think this is where the problem lies i could not understand why after shutting engine off hours later and engine cool still lots of pressure when undoing Expansion bottle cap, thank you for the link and advice everyone
If it's pressurising with the engine off then this must be your problem.
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Re: P38 Rangie 4.6 pressure in water system

#6 Post by falconho » Wed Jan 02, 2019 7:06 pm

Hi ive ordered a vaporizer overhaul kit from Tinley Tech, you say LPG Reducer do I need one of those too, sorry for my ignorance lol also the tinley tech man said to be careful undoing the screws as they go into the waterways and corrode in very tight I will backward and forward them carefully, been in motortrade 35 + years this LPG all new to me but willing to learn.

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Re: P38 Rangie 4.6 pressure in water system

#7 Post by Brian_H » Wed Jan 02, 2019 7:19 pm

Vapouriser and reducer are different names for the same thing. It might be an idea to get a suitable joiner for the two coolant pipes just in case you need to run it while the unit is off being repaired if its your only vehicle, less of a problem if its staying where it is.

Did you manage to test to see if it was the cause, or replacing anyway?

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Re: P38 Rangie 4.6 pressure in water system

#8 Post by falconho » Wed Jan 02, 2019 7:56 pm

Hi fortunately not my only car have switched to petrol only and seems to not be pressurising was going to take it for road test and air suspension decided its not going to play the game anymore and sat on its arse lol but that's another story im dealing with, it rains then it pours anyway have had it ticking over for nearly 2 hours holding it at 2000 revs for a while etc no pressure so hopefully on the right track

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Re: P38 Rangie 4.6 pressure in water system

#9 Post by Brian_H » Wed Jan 02, 2019 8:05 pm

Does sound like it, If you need help with the air suspension then the site Gillbertd posted above may be able to assist.

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Re: P38 Rangie 4.6 pressure in water system

#10 Post by falconho » Wed Jan 02, 2019 8:15 pm

Hi yes I have a new compressor on its way to me from one of the very helpful forum regulars.

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Re: P38 Rangie 4.6 pressure in water system

#11 Post by Gilbertd » Thu Jan 03, 2019 12:03 am

That'll be Marty then.....

Notice that you joined the pub, what diagnostics do you have for the EAS?

Sounds like you have confirmed it is a leaking reducer. Depending on what reducer you have fitted, a new replacement isn't a bad idea. Not only won't it leak but it'll save you a lot of grief with seized screws.
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
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Re: P38 Rangie 4.6 pressure in water system

#12 Post by superkp » Fri Jan 04, 2019 7:28 pm

I had a 3.0 v6 audi with this problem you could smell gas in the header tank it was diagnosed as reducer leak

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Re: P38 Rangie 4.6 pressure in water system

#13 Post by Gilbertd » Fri Jan 04, 2019 8:22 pm

Problem is that a lot of places mistake the smell of the Ethyl Mercaptan odorant that is added to LPG for combustion gases, particularly once it has been bubbled through the coolant. They will also often use a sniffer to detect hydrocarbons in the coolant header tank so mistake the Propane hydrocarbon for combustion gases. The only way there would be hydrocarbons in the coolant on a petrol only car would be from a head gasket leak.
'96 Saab 900XS, AEB Leo, sold
'93 Range Rover 4.2 LSE, Lovato LovEco, sold
'98 Ex-Police Range Rover 4.0, Singlepoint AEB Leo, my daily motor
'97 Range Rover 4.0SE, eGas multipoint, a project.....

Proud to be a member of the YCHJCYA2PDTHFH club.

falconho
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Re: P38 Rangie 4.6 pressure in water system

#14 Post by falconho » Fri Jan 25, 2019 10:59 pm

Hi all an update, has taken me a while to reply as have had a air suspension problem leak that has taken a while to find and rectify, a small hole in silencer was blowing hot gases on to air pipe hidden behind silencer on top of chassis, can now drive car and can report its running the best it ever has with the new vaporiser no overheating or pressurising of water system, happy days, was just wondering I just bolted on the vaporiser straight out of the box and its running great good performance and tick over have I just been lucky, do you think I should have the tuning checked Ken.

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Re: P38 Rangie 4.6 pressure in water system

#15 Post by Brian_H » Fri Jan 25, 2019 11:53 pm

Ideally you want to check/set the pressure to what it was before in most cases, but I suspect BRC is a bit special in that respect, It would help if you could post the model of reducer and ecu you've got, as some of the BRC kit handles the map differently to others (not 100% sure you can adjust the pressure on all BRC reducers either because of this)

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Re: P38 Rangie 4.6 pressure in water system

#16 Post by LPGC » Sat Jan 26, 2019 10:19 am

Adding to what Bri said, BRC reducers usually come preset at pressures such as 1200mb / 1500mb (1.2 / 1.5bar). Some have a little rubber cap placed over the pressure adjuster (allen key socket), pressure is adjustable over a wide range (after removing the cap obviously). If the install has BRC injectors with nozzle size well suited to the engine the original reducer's pressure was probably just set at one of the factory default pressures (again 1.2 or 1.5 bar) in which case your replacement reducer's pressure setting should be a good match to the original reducer's pressure setting. But it is worth checking pressure and calibration.
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Re: P38 Rangie 4.6 pressure in water system

#17 Post by falconho » Sat Jan 26, 2019 6:00 pm

Hi managed to get details off of Vaporiser before it rained haven't had time to find or get details of ecu yet, so the Vaporiser details are BRC/IMPCO Genius Max 1500 M BAR 18 DA SN/10029 is there somebody in the South London Surrey area that could check this for me, im new to lpg and have not had any work done before so any recommendations I would be grateful. Thank you Ken

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Re: P38 Rangie 4.6 pressure in water system

#18 Post by Brian_H » Sat Jan 26, 2019 8:18 pm

I'd suspect (and Simon would be the easiest bet to confirm) that will be a mixer type system with the mention of IMPCO there - if it is that might make adjustment somewhat different. Might help to know if the p38 is a GEMS or Thor for him to give you better guidance. If your not sure if your intake manifold is a rectangular box its GEMS, if its more like a bunch of bananas its Thor.

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Re: P38 Rangie 4.6 pressure in water system

#19 Post by LPGC » Sat Jan 26, 2019 10:18 pm

If it's a 1500mb BRC / Impco reducer it'll likely be a sequential system Bri.

Some of the Impco mixer systems use a reducer with characteristics that are more akin (or identical) to a sequential system reducer than to the usual type of mixer system reducer, a reducer that outputs gas under pressure rather than a reducer that outputs gas at near atmospheric pressure.. such as BRC 1500mb (1.5 bar output) reducers, the same model reducer as used on many BRC sequential system installs. This is in stark contrast to what we usually think of when we think of a mixer system reducer's properties because most mixer system reducers output gas at very near atmospheric pressure (the mixer unit just causes a slight vacuum 'signal' to the reducer causing the reducer to output gas because it sees 'signal' as lower than atmospheric pressure).

The 'mixer' on some Impco systems isn't what we usually consider a mixer... The mixer component of most of the mixer type systems we think about is simply a slightly engine air intake restrictive hole with a gas entry point after the restriction, the restriction causes a slight vacuum on the engine side, the slight vacuum 'signal' causes the reducer to send gas to the mixer... so more airflow causes more vacuum signal to the reducer so the reducer flows more gas to the engine. We might consider that (in petrol terms) with our usual mixer type systems a complete gas carb would comprise both the mixer (just a simple standalone venturi with a gas entry point) and the reducer (jets, float bowl, etc). In contrast some of the Impco system mixers are more akin to a standalone complete gas carb (venturi, jets, in some ways the float bowl, all rolled into the 'mixer component') with the reducer basically just performing the function of the fuel pump, the reducer doesn't have to be load sensitive etc because the Impco gas carb performs all of the gas metering functionality, it has moving parts unlike our normal mixers.

Impco is American, that's well known. It's probably lesser known that BRC (usually known as an Italian LPG system manufacturer) is owned by an American firm. There aren't many American vehicle LPG system component manufacturers so perhaps no surprises that some Impco gas carb type systems use BRC positive pressure reducers.

Most Impco branded (not Impco/BRC branded) reducers output gas at higher than manifold/atmospheric pressure but at much less pressure than Impco/BRC branded reducers. But, for the ability to switch to gas at low reducer temperatures the lower pressure output Impco (Impco only, not Impco/BRC) branded reducers are better - Easy to understand why, it's because at the cold temperatures a reducer might reach ('heated' by water from a cold engine) LPG stands more chance of evaporating/atomising properly at the lower pressure. Engines with mixer systems can usually be started on gas - partly due to 1 The mixer system working standalone from the petrol fuel system, so not under electrical instruction from the petrol system, so not appyling cold start enrichment (which is not necessary and is adverse for starting engines on LPG, and partly due to 2 The lower pressure output of a mixer system reducer means gas will evaporate at a lower temperature. But if a mixer system uses a reducer that outputs gas at sequential system pressures we lose the advantage of 2.

BRC / Impco 1500mb GeniusMax reducer https://tinleytech.co.uk/shop/lpg-parts ... vaporiser/

Seems I've written quite a bit about BRC gear on forum recently... It may seem I don't like the gear but that isn't necessarily true. I do really like the reducers, they're great bits of kit though they are overly expensive and starting to seem maybe a bit old fashioned on the performance versus physical size (overly large) and cost fronts. BRC own brand (not GFI) injectors are good too, but they are very large by modern day standards and being large isn't a good thing because one aspect of doing a good install is to have short pipe runs, while large physical size of injectors can be a hindrance to that. I like BRC brand injectors but I don't like their size. I don't like BRC electronics (ECUs) and on some BRC systems the lack of a runtime manifold pressure sensor. In my opinion most of the BRC installer network don't seem very clued up.. but that might ought to be expected from an installer network that involves mostly people who do mostly other (none LPG related) garage work most of the time. Could say that the policy of the prior BRC importer boiled down to selling kit mostly to garages that generally fitted more brake pads than LPG installs... hardly knowing what day it is in LPG terms but knowing how to charge high prices - Which are two of the reasons why I would struggle to know of a BRC dealer/installer to recommend to someone who would prefer results to going through the motions.

Simon
Last edited by LPGC on Sat Jan 26, 2019 11:13 pm, edited 2 times in total.
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Re: P38 Rangie 4.6 pressure in water system

#20 Post by falconho » Sat Jan 26, 2019 11:05 pm

Hi yes its a Thor 4.6 P38, Its the same vaporiser as in Tinley tec link also purchased from them Ken.

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