Saint.V8

Saint.V8

Dyed-in-the-wool 100% RR Junkie
Full Member
Dont need this to degrade into a L322/P38 argument or a 'How useless blah blah this or that is' etc.....

On holiday and if sitting for a couple of minutes the temp will creep up, start driving and it will drop back down again.

Parked back at the cottage and the expansion tank cap was releasing coolant and the top hose was hard. Left to cool slightly and released the cap, lots of gurgling and bubbling.....took about 6 litres of coolant to replace what had been lost, then started engine and when up to temp, the expansion tank start to pour coolant out at a fair rate (had left cap off to prevent over pressure).

With engine off and hot, viscous fan can be spun by hand and will complete about a revolution and a half before it stops, so could it be the viscous isn't cooling enough, the stat not opening fully or something more sinister?

Engine runs great no hiccups or loss of power, no smell of exhaust in the cooling system.....ideas ???
 
Sounds like it could be viscous related ?

Was the internal cabin heater on during this journey ?
 
ant it might just be a airlock which has lodged hard somewhere due to your recent rad change,be carefull it will spew the lot out if cap left off as it runs pressurised to lower boiling point.dont cook it as it will die without doubt. is there a a/c fan mod poss to aid tempory ? I always top up header very very slow whilst engine running if water has been drained.if in doubt enjoy your break & phone a recovery for return journey it could end up cheaper in the long run m8
 
+1, given you changed the rad very recently, I would guess an air lock in the system.
Needless to say, I'm assuming you bled the system properly with heater on etc?
Did the AC fan kick in to aid in cooling?
 
Last edited:
Cheers for the responses chaps, regards bleeding, I employed the same method I used when I did the rad previously, that being said it does seem air lock related....

Not driving with cap off, just running at idle up to temp stationary....

A/C fans did cut in to aid cooling, I am thinking viscous related as after the temp rose, the whole journey back while moving temp remained in the 105 to 110 range.

Going to find a place to see if I can get hold of a viscous unit and stat, as the holiday is in the Isle of Wight and we are staying in a cottage in the middle of nowhere so have to drive to do stuff!!

Will check in the morning and rebleed the system and find a spares place!
 
Could be the bottle top cap you lost when changing rad:D:D:D








When up to temp, stat open, with expansion cap off doing some short reving blasts may help.
If those beast are as difficult as the P38 can be, I find it takes a day to fill coolant system properly with the cooling down period
 
Druim said:
Could be the bottle top cap you lost when changing rad:D:D:D








When up to temp, stat open, with expansion cap off doing some short reving blasts may help.
If those beast are as difficult as the P38 can be, I find it takes a day to fill coolant system properly with the cooling down period
Click to expand...
Managed to get the cap out, during the vid before I start the engine, I disappear under the car to retrieve the cap and refit the 3 pipes underneath!!

Good spot though:D
 
Sounds like a typical viscous fan failure to me. If it were the stat it's unlikely it would cool down when you are moving whereas the ram air would render the viscous unnecessary.
 
Datatek said:
Sounds like a typical viscous fan failure to me. If it were the stat it's unlikely it would cool down when you are moving whereas the ram air would render the viscous unnecessary.
Click to expand...
That is indeed my primary diagnosis, local auto factors on the island have ordered one in for me for tomorrow, so will change and see if this helps. Also ordered a new stat too, cos yer never know!
1992lse said:
also sounds like a weak water pump.
Click to expand...
Many thanks for the advice, water pump was changed in Jan 2013, so hoping it would last a bit longer than a year and a half, but is certainly worth looking in to.

There is flow through the expansion tank bleed screw, which suggest coolant flow. But will check after fitment of the viscous fan.
 
naughty boy, should of changed thermostat when you done water pump.
if you got good flow then it must be the fan.
 
Saint.V8 said:
That is indeed my primary diagnosis, local auto factors on the island have ordered one in for me for tomorrow, so will change and see if this helps. Also ordered a new stat too, cos yer never know!

Many thanks for the advice, water pump was changed in Jan 2013, so hoping it would last a bit longer than a year and a half, but is certainly worth looking in to.

There is flow through the expansion tank bleed screw, which suggest coolant flow. But will check after fitment of the viscous fan.
Click to expand...
That would say that it's not the stat or the pump. LPG problems?
 
1992lse said:
naughty boy, should of changed thermostat when you done water pump.
if you got good flow then it must be the fan.
Click to expand...
Search my threads, stat changed a while back, a few months after I got the car as I was getting curious gauge readings, ended up being a duff heated coil in the stat body.....
Datatek said:
That would say that it's not the stat or the pump. LPG problems?
Click to expand...

No LPG issues, rebled the system this morning and headed out, no issues so far, so may just have been a huge airlock that had caused a hot spot and the coolant started to boil out.

Still gonna change the viscous fan coupling tomoz and see what happens.

Undone the expansion cap bleed screw and revved the engine to about 3k and the coolant was shooting about 10 foot out of the bleed hole, so plenty of flow from the pump!
 
Saint.V8 said:
Search my threads, stat changed a while back, a few months after I got the car as I was getting curious gauge readings, ended up being a duff heated coil in the stat body.....


No LPG issues, rebled the system this morning and headed out, no issues so far, so may just have been a huge airlock that had caused a hot spot and the coolant started to boil out.

Still gonna change the viscous fan coupling tomoz and see what happens.

Undone the expansion cap bleed screw and revved the engine to about 3k and the coolant was shooting about 10 foot out of the bleed hole, so plenty of flow from the pump!
Click to expand...
I know not a lot about LPG but I wondered if there was a leak of gas into the water from the vapouriser?
 
Datatek said:
I know not a lot about LPG but I wondered if there was a leak of gas into the water from the vapouriser?
Click to expand...

That is a possibility, although I would have thought the charactoristic LPG smell would be evident in the coolant system, but is certainly something to check if it continues to prove troublesome.
 
im still with airlock ant but tbh over pressure is what could have wiped out your old weak rad.as keith said it could be possibly lpg related even if you cant wiff it don't rule it out.recently my d2 lpg had 1 of the twin vaporisers fail internally so water was slowly getting into the lpg injectors.it actually wiped out all 8 lpg injectors & I ended up fitting a total new lpg front end,
 
I seem to remember MrGorsky had pretty much the same symptoms on his P38? He runs on LPG too. Cannot remember the outcome though.
 
UPDATE:

Rebled the system on Tuesday morning and she was happy as a sandboy.

Fitted the new Viscous Coupling this morning and still (fingers crossed) behaving itself.

Hopefully it was just a large airlock that created a steam void and blow the coolant out!
 
I had this on my holidays too a few weeks back Saint. Diagnosed weak viscous as it wasn't kicking in at all despite way overheat (115deg). Any how after loosing the car for a couple of days whilst the garage sourced and fitted a new viscous, it was back with me and overheating again within 5 miles. Much head scratching and a feel of the bottom of the rad revealed it was stone cold. Both electronic and mechanical side of the thermostat had given up. Ironic as Id replaced both it and the pump the month before so I didn't have any issues on holiday ! Luckily the garage that did the work on the fan helped me out by popping the innards out of the stat for the price of a good beer and I was on my way again. Back at home I tested the stat on the bench and almost had it red hot before it opened, it was well and truly fecked.
May be worth noting anyone finding this thread that these engines run hot at 105 deg so any weakness in the cooling system shows up quickly.

After fitting a new stat I monitored the temp real close for a few day - running about 104 to 107 deg with mixed driving is normal which ties in with the 105 deg stats.
 
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