Hot starting problem

The Original Tom · Post by **The Original Tom** » Sun Jul 29, 2007 3:38 pm

I've recently (from yesterday actually) started having trouble with hot starting.
I removed the fixed fan (not viscous) and replaced it with 2 electric cooling fans just before this happened. The temperature stays at a nice level, about the same as it did before so it doesn't appear to be getting over hot.
It won't start on either petrol or gas when hot, and it takes ages to get it to even start sounding like firing, then it splutters into life. Once started it runs fine.
I used to have a problem with vapour-locking making the vehicle stall, so I've moved the fuel lines so that they come straight up from the inlets, and over the dash-pots back to the supply.
It's a 3.5 on SU carbs.

Any clues?

The Original Tom · Post by **The Original Tom** » Mon Jul 30, 2007 6:34 pm

No-one? Someone must have a suggestion... pretty please?

sowen · Post by **sowen** » Mon Jul 30, 2007 7:53 pm

Is the engine flooding or is there not enough fuel coming up? My hot start problems are flooding. I know this because there is a heavy smell of petrol in the vicinity of the engine and exhaust, and simply spinning really quick for a long time before quietly drifting into life. Its not something that happens often though, and to prevent it I lift off the loud pedal shortly before I shut it down if its proper hot. The only option I've got when it happens is to pop the bonnet and wait

Maybe you need the cooler air constantly running over the carbs and stuff to keep them cooler, as your gauge is only telling you the water temperature in the engine. Either run one of the electric fans continuously or try putting the fixed fan back on.

Simon

The Original Tom · Post by **The Original Tom** » Mon Jul 30, 2007 8:23 pm

The electric fans don't shift as much air as the fixed one did - by a long way! The fixed one was super inefficient and actually made revving the engine sluggish! I don't even want to imagine how much power it was sapping running at about 6000rpm!
If I have to, I may put a charge-cooling scoop, or possibly even a bike fan mounted on top to cool the carbs.
I don't know why I chould have this problem though? Many people seem to put electric fans on a V8 in a land rover, but this problem isn't a commin AFAIK.
Also worth noting I do have the plastic carb inslating spacers between carb and manifold, and although they still get hot, it's not as hot as the manifold!

Oh, and I finished wiring the fans into the thermostat today, turned it over and it started instantly!

sowen · Post by **sowen** » Mon Jul 30, 2007 8:42 pm

I've got a single 13" kenlowe mounted infront of my rad, standard series 4 cylinder 4 core jobbie, with the standard bulb sensor in the top hose controlling the thermostat, and a 1/2" - 3/4" gap all round the bonnet, and I have about 3/4" clearance between my p6 water pump and rad, so fixed fans are a no no for me. My heater is permanently on just in case. I've had no problems except for when I get a little enthusiastic

.

If you want extra air flow for cooling in the engine bay I think outlets at the back of the bonnet may be more beneficial than a scoop at the front, but I could be wrong. I can't remember which is more efficient, but the outlets do help raise cabin temperatures with the windscreen vents open during summer

. Not experiencing this kinda problem much I haven't been able to experiment too much with scoops and vents.

I think all twin carb set-ups on the rover v8 would have the insulating spacers fitted as standard.

The Original Tom · Post by **The Original Tom** » Mon Jul 30, 2007 9:06 pm

Yep, the spacers are standard, but thought it was worth noting.
I have 2 fans behind the rad from a Disco 2. These are run off a thermostat that comes on at 90*. I also have a single 13" kenlowe left over from when it was a series engine (then, this was the only fan!). The 2 fans honk out an incredible amount of heat when it's running, and this could be blown over the carbs heating them up. With the fixed fan it span so fast that the air it moved was always cold.
It's the original radiator, because the 2.5p engine uses the same rad out of the factory as the V8, and it's in not-bad condition. I also flushed it well before fitting the V8.

I was going to try to avoid cutting ruddy great holes in my bonnet, but it looks like I might have to now.

What do you think to the idea of putting a small grille above each carb, and a cooling fan from a PC case on each one?
I could put a timer delay on them too so that they are on all the time the engine runs, and then stay on for x minutes after the engine switches off.

sowen · Post by **sowen** » Tue Jul 31, 2007 7:12 am

You could also try fabricating some type of heat shield/baffle to direct cooler air over the carbs and hotter air away. I have no idea how good pc case fans are, but beware of the rain if you cut holes above the carbs in the bonnet.

Simon

The Original Tom · Post by **The Original Tom** » Tue Jul 31, 2007 10:33 am

Good point about them dying in the wet

A baffle wouldn't really work as the entire under bonnet gets really hot any way. I think an extractor fan is teh way to go.
So. Does anyone have a bike radiator fan they no longer need that they could let go for a few pennies?