Volvo C303 - A low emissions vehicle?

Conversion to LPG (propane)

 

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Fitting Plan        LPG fitting photos        Running on LPG      So what went wrong?    Electronic Ignition     Final chapter?    5,000 km later

I felt that as there was so much information coming from this seemingly straightforward job that it deserved it's own page.  It has been a serious learning experience and I've had to do a whole series of jobs that were more urgent than I realised just to get the truck to run properly never mind on LPG. This page is dedicated to my ongoing struggle to get a 30 year old vehicle to a high mechanical standard without spending a huge amount of money (Aye, right) and without compromising reliability.  This has been complicated by some parts having been unavailable for over 25 years (Bosch ignition coil) and others being seriously expensive. I have chosen to keep things in chronological order rather than logical as this will explain my thought processes and voyage of discovery.

 

Apart from some basic maintenance there is little that the Volvo requires in the way of mechanical development, however given the price of fuel and that I get about 12mpg I have been looking at changing the engine for either a big V8 with fuel injection or a big diesel.  Both of the options are fraught with hazards and would mean many weeks work and/or loads of cash.  The most cost effective option is LPG (propane) conversion.  I have this in my Kia Sorento 4x4 and saving over 50p per litre is very nice but most mechanics have advised me against converting a carb fed engine because of the danger of backfires.

Tony at Tinley Tech was extremely helpful and having spoken to a number of people who've converted twin carb V8s and V6 Jeeps, it seems relatively straight forward. I've taken delivery of the kit including the injector/mixers and a 110 litre tank (actual capacity 96 litres).  I'm told it'll take 2 days to fit so long as you spend a few hours reading and understanding the instructions and planning the install.

As usual, once you start trying to make and old vehicle run properly you end up transferring the weak point and showing up underlying problems.  So with sorted carbs I've now (hopefully) got a leak between the exhaust and inlet manifolds.  They are known for it and since last week the CO figure has gone from a healthy 3% to a dangerous 0.5% with a lot of engine noise and poor running and hunting. It runs like a dog on LPG. I loosened a suspect nut on Cylinder 6 fitted a new holding washer and retightened and, Lo and Behold, the CO went up to 4.5%.  So off come the manifolds, new gasket on and hopefully that will be full power and smooth running restored!

Fitting Plan
 The tank will fit nicely behind the rear seat where I currently keep the spare wheel (where THAT will go now, I don't know) with the filler on the side behind the driver's side rear passenger door.  All pipe work has to be run under the vehicle

LPG fitting photos

tank fitted behind the seats

Seat folded forwards to show the winch batteries

petrol cutoff solenoid

LPG cutoff solenoid

LPG solenoid (brass bit under airbox)

LPG control switch beside winch control panel

LPG vaporiser (top right)

 

Running on LPG

It's a bit more involved than my Kia which just works automatically.  First you start up on petrol, running it for a few minutes to get some heat into the engine.  Without some heat the LPG will not vaporise properly.  Once it's warmed a bit the control switch on the dashboard must be put in the "all off" position until the petrol in the carbs is used up, then as the engine falters you switch onto "LPG only".  Once warmed it'll start perfectly on LPG.  Also I have to do is remember to switch to petrol for 30 seconds before I stop for the day to refill the float bowls, otherwise I have to crank for a while to get it started.

The first refill was only 71 litres (I expected 88 litres to get into a 110 litre tank at 80% of fluid capacity)  the next ones will be better as whatever air is left in the tank is absorbed leaving more space for gas.

LPG is very sensitive to a badly setup or faulty engine so if there are any problems they will quickly become apparent.  Oh boy, do they show up!  Read On.

So what went wrong?

At first it was smooth and cheap but it soon started to go wrong.  As I should have realised, worn carbs were the least of the problems and the super rich running was masking several other problems. 

After the first tank of gas it started to run very badly on gas and poorly on petrol and when put on the emission analyser the reading was a very unhealthy (lean) 0.5%.  The cause was identified as a leak at the manifold probably from the gasket breaking down.  I got a new gasket and spent 4 hours (with help) changing it over.  As you can see from the photos below there were several breaches on both inlet and exhaust parts and this was letting air in causing rough and very lean running. Once changed it was all smooth and settled on petrol but still underpowered, on LPG, however it was still horrible and needed set up again professionally.

Once again I was back at the garage attaching the gas analyser to the exhaust.  On petrol we had an ideal 3.5% to 4% on idle, rising to 6% or 7% at speed.  This may be slightly rich but I'd rather that than lean and in any case there is no real adjustment on these carbs.  On LPG we played around until the figures were basically the same and everything was smooth and even.  All I had to do then was test drive it.  Within a few hundred metres it was clear something was still wrong.  On idle it was fine, on  a smooth open throttle without load it was also fine if a tad rough but under load it was awful.  It was almost as bad as ever with inconsistent roughness, refusing to pull through the higher gears and unable to go over 60KMH.  Back to the LPG Guru who identified an ignition problem causing a weak spark and misfiring.  BUGGER!  I had replaced everything I could before fitting the LPG so only the coil and condenser was left.  The coil is unavailable and the condenser is from Germany only.  What was I to do?

Electronic Ignition

With no new 24v coil and condenser I had to look at other options.  A friend with more experience of fitting LPG to old, odd vehicles told me that the timing of carb fed LPG engines was critical and that I would have to consider electronic ignition.  The best aftermarket system is called Lumenition but is 12v only.   This is not really an insurmountable problem but means I would have to fit a second, 12 volt ignition switch. This would not, however, compensate for what I finally realised was an ignition problem caused by a seriously worn distributor.

Deeper and deeper I sunk. I was now looking at £500 for electronic ignition, a 2nd ignition switch system and a new distributor, if I could get one.  Thank goodness for our Yahoo group and Aryan Schmitz who told me about 123ignition. This is a fantastic piece of kit.  It replaces the standard distributor with an exact replacement (the manual even says TGB13 C303/C306 B30A engine) with multi map electronic ignition built in.  I still need the 12v ignition circuit but that is about £2.50 of switches and wire and 15 minutes work.  Best of all it removes any questions about sticking dizzy weights, worn shaft, dodgy vacuum advance/retard system whilst giving a 100% reliable maintenance and wear free LPG map solution.  The cost is a very reasonable £210 (plus shipping and new coil).  LPG, it seems, has an octane rating of 112 compared with 92-95 octane unleaded fuel and very different burn characteristics which require a different timing/advance/retard system to gain best advantage.  The 123ignition system claims that without any hassle.

So it arrived and is looks very simple to fit.  I wired in a switch to the dash running on 12v (which feeds the LPG system - doubles as an extra immobiliser) to act as an ignition control switch. Removed the old dizzy and found it was seriously worn and, on dismantling, that the physical integrity of the advance mechanism was fully compromised (i.e. it was f**ked!).  The new one was quite simple to fit although there was a lot of climbing in and out of the truck to get the static timing to 10o .

Time came to start it up and test drive.  I fired it up on petrol and it started perfectly (phew!) but ran really badly (Oh Oh) but only took a few minutes to warm enough to change to LPG.  Before I could do so though it stalled.  I double checked everything , started it again but after 30 seconds it stalled again.  I switched to LPG and it started fine and ran BEAUTIFULLY.  I took it for a test drive and it was smooth, even powered right through the rev range with noticeably more power at the top of the rev range and more torque at the bottom.  As for fuel consumption time will tell, but I am delighted.  Why did it stall on petrol?  It had run out!

 

Final Chapter - a weekend's playing at Drumclog

I spent 2 days driving and camping at a local site with much getting stuck and driving over unfeasibly difficult terrain showing Landrovers up.

Normally I allow for 70 litres of petrol per day (cost for the weekend £135) but I used only 85 litres of LPG in 2 days (cost £35 - saving £100). It ran beautifully without missing a beat, starting from stone cold each day.

The performance on road is still disappointing with hills posing a problem but them I am using 37" tyres. Off road it is simply amazing, pulling cleanly from tickover in 3rd gear with most driving done in 2nd. It is smooth once warmed and starts easily.

As for sleeping in the truck .......
I assumed that a stretcher is really just an orange camp bed with handles and that a pair hung in the back of the TGB13 (a nicely panelled/insulated and well lit one) would be perfect. WRONG. We froze (2C) and bashed our head getting in and out of bed. My 7year old was better then I however as she could curl up and had the jackets over her.

The plan now is to make some kind of fold up board to hang on the lower stretcher points and cover the whole area so I can sleep on an inflatable mattress. And get a heater!!

The 123ignition made a massive difference to fuel consumption and driveability and I am a very very happy boy

 

The Final final part? - 5,000 km later

Having done the above mentioned 5,000 km I found that low down power was getting worse and worse with me having to ride the clutch to get the truck moving.  Over about 1500 rpm it was ok but it was seriously fluffy at low revs, off road it was not enjoyable.  The engine was rough and noisy.  So I spent some money on Lucas Oil Stabiliser and new plugs and oil filter and it was slightly better but still ran rough when Aryan mentioned that he was suffering valve recession (the valve seat was being eaten away by the lack of  lubrication in the fuel) and was having to redo the valve clearances every 2500km.  He noticed that his engine ran badly at low revs but a top end service fixed it right up!  I checked the valve clearances, setting inlet to 0.5mm and exhaust to 0.6mm and started the engine  .......... and it was lovely.  It ran smoothly and quietly and had all its creamy smooth low down torque again.  Unfortunately it did not last long with performance going off within 500km.  The answer? A refurbished head with hardened exhaust valve seats and guides, easily and cheaply done

Finally, the final part

The engine was dying. Simply put but tricky to fix with valves dropping, cam followers dished small and big ends away.  The physical integrity of the engine was compromised. It was an ex engine it had ceased to be.

I fitted e new (,20,000 km) engine and all is well.  I've not fitted the head as I didn't want to tempt fate again!