The V8 Owners Forum -

Hi All
After what seems like forever I have finally got my car MOT'd and taxed
When the engine was being set up in the garage (no air flow around the car to speak of)the temp stayed pretty good although it did climb a bit higher than I normally like to see but cooled down really quickly once the fan fired up.
Now when I have taken it out for just a few short runs the temp goes up too quickly and stays up there even with the fan on.
I have opened the bleed valve in the sysytem and run the motor for about 10mins and it seemed okay,a little bit of air came out but not masses.
I have changed the thermostat and drilled 2x holes in it(82 not 74which I asked for but did not check before drilling ).
Getting to the heater hoses is a nightmare to back feed the system.
Will it help to drain the sysytem again and then refill really slowly and run the motor up when about 3/4 full and keep going until it is completely full?
My rad is an all ali unit which is well up to the job and I have a 16"pusher fan installed.
Any and all advise welcomed guys.
Cheers
Paul

Hi
Is the fan running in the right direction? filling the cooling system whilst the engine is running usually helps. Can the hot air get out from the engine bay ok? do you have a shroud around the rad to stop hot air just going round to the front of the rad and cycling through?
Bets regards
Mike

I'd go with Mike

Fan blowing forwards thus creating stalled air at slow speeds (Will not be the first - Mine started that way too!)

Ian

If oyu can, run the car up a set of ramps and fill the coolant with the engine running.
We used to do that on some of the Hondas at work, but used the front legs of a 2 post lift to raise the front about 18 inches or so.

Hi All
Fan is running the correct way but without a shroud as there is just no room for one.
I am going to drain the sysytem down and then half fill and then fire up and continue to fill with the front of the car up in the air.
will keep you posted.
Thanks for the help already.
cheers
P

If you are running an Eddy 180 manifold then there is a drilling mod that is worth doing to it. The mod totally sorted out my mates 3.5 lump that was always overheating. Mine you he did fit a 74 degree stat in at the same time.

Hi lads
Drained down,refilled with motor running and got a fair amount of air out,but it still seems to be getting a bit hot.
Am going to see if I can get an adjustable screw in fan switch.
Pete ,my manifold is the eddy rpm 35.1 rover manifold.
What is the mod please and does the 74 stat make a great deal of difference?
Cheers
P

Hi Paul,

The manifold mod involves drilling two holes in it, check out the link below:-
http://how-to-build-a-pilgrim-sumo.wiki ... e-plumbing

I made my holes about 7mm diameter.

If you are running one of the bigger RV8 blocks then the 74 degree stat is worth having. My lump runs at just under 80 degrees with this stat. My fan kicks in at about 83. JRV8 or V8 Tuner sell stats.

Cheers,

P

Hi Pete
Thanks for that.
Have now got a 74 stat and the correct temp sender unit(this may well have something to do with the guage reading high!!)
Will try the mods out tonight.
Will keep you posted.
Cheers
Paul

I agree with the ramps tricks, but make sure it is the front of the car you put on them.

One trick for bleeding is to cut the bottom out of a large Coke bottle, then gaffer tape the bottle upside down into your the rad neck, like a large funnel, and fill the Coke bottle with coolant, whilst running the motor. This way it becomes by far the highest point, and less chance of bubbles and stuff sneaking by and back down into the cooling system. They are far more inclined to follow nature and head upwards

You can also see bubbles burping their way out too, which is weirdly satisfying.

gelmonkey wrote:Hi Pete
Thanks for that.
Have now got a 74 stat and the correct temp sender unit(this may well have something to do with the guage reading high!!)
Will try the mods out tonight.
Will keep you posted.
Cheers
Paul

I drilled two extra holes in my 74 degree stat but I found that it took ages for my engine to heat up in cold weather. I've now blocked them off so I just have one hole of about 4mm in the stat (At the top). My running temperature has gone up maybe 2 degrees to around 78 which is still OK.

Watch out when fitting the stat housing as the actual stat has a habbit of dropping out of position without you noticing.

Drilling the holes in the manifold whilst it is still fitted to the car can be a bit tricky but it is do-able. (clean out all the swarf!)

Paul and Pete
I guessed the front had to go up
As for ther burping ,the coolant was doing that but I'm not sure if it was me doing the burping aswell as I had just had a fizzy drink.
Thanks for the help all the same

Pete
I will try the 1 hole in the stat and the new sender unit first without drilling the manifold.
I desparately want to debut at the South Coast Nationals next weekend at Beauleiu but am not sure if it going to happen.
I will be going for sure but it may be in my stunning gelcoat spattered works van, MMMMMMMM.

Will come back to you all later and let you know how it has gone.

cheers
Paul

Show us a pic of the engine Paul!
Deffo stick a 4-5mm hole in the thermostat flange at the 12 o'clock position. I use an 82C stat with a thermo switch in the top hose set to 88C. This means I get proper cooling at full water flow with max effect.

Where is the sender unit for the temp gauge??
Are you sure its giving a correct reading?
Is your expansion tank connected to a stub in the top header of the rad?

I never had to drill holes in my 351 manifold. Can someone explain why those holes in the sumo pics will make cooling any better?
And why wire up two fans in series? Wont they run slower??
If I wire to 100 watt lamps in parallel I get 2x100 watts. If I wire 2x100 watt lamps in series what happens??

Just my thoughts
Probably wrong as usual.

mgbv8 wrote:Show us a pic of the engine Paul!
Deffo stick a 4-5mm hole in the thermostat flange at the 12 o'clock position. I use an 82C stat with a thermo switch in the top hose set to 88C. This means I get proper cooling at full water flow with max effect.

Where is the sender unit for the temp gauge??
Are you sure its giving a correct reading?
Is your expansion tank connected to a stub in the top header of the rad?

I never had to drill holes in my 351 manifold. Can someone explain why those holes in the sumo pics will make cooling any better?
And why wire up two fans in series? Wont they run slower??
If I wire to 100 watt lamps in parallel I get 2x100 watts. If I wire 2x100 watt lamps in series what happens??

Just my thoughts
Probably wrong as usual.

The web site is my mates, if he has showed the fans wired up in series then he is a di*k head!

The fans that Pilgrim supply are crap anyway, I've ditched mine for one 14" Pacet Pro fan, it pulls less amps and moves more air.

The idea of the holes came from someone on this forum I think. Also Jim of JRV8 was looking into this mod. Infact if you look at the dual port Offy manifold it has the holes (so I've been told). The theory is that the coolant seems to stagnate around the back of the thermostat forming a cold spot so what happens is that it boils in the heads before the stat opens, the holes allow some circulation so the cold spot does not form. Not all engines seem to suffer the problem, my 3.5 was always OK (I did have the 74 degree stat fitted though). My mates car would over heat within 2 miles of driving, he drilled the holes and replaced the 82 degree stat with a 74 degree one and the problem was solved. My 4.6 has always been OK but I drilled the holes and run the cool stat.

After speaking to Paul tonight I don't think that the engine is overheating at all, its more likely a sender/gauge mismatch. He is going to do a cailbration test with the sender wired up and dunked in hot water along with a thermometer.

Just in case I've caused any confusion, I also have one hole in my stat at the 12 o clock position.

I'm paranoid about dropping a liner even though I have a red grade block (Des Hammills book is enough to put the willies up anyone). This is why I run my engine at 78 degrees, the fan is controlled by an electronic switch that I made, it kicks in at 83 degrees and cuts out at 80.

""The theory is that the coolant seems to stagnate around the back of the thermostat forming a cold spot so what happens is that it boils in the heads before the stat opens, the holes allow some circulation so the cold spot does not form.""

The hole in the top of the stat flange does the same job doesnt it?