OP, I have one word for you...Vermin! Your problem has reminded me of an identical problem on a MKII Jaguar some 16 years ago. The owner had left his cooling pipes off his car during winter. Come springtime he installs new hoses, filled the system, runs the car up to correct temperature and...WHAM, a blockage in the system causing BIG overheating. He changed all sorts of components, scratching head for many days...eventually flushing and reverse flushing his radiator when out flowed two dead mice, seriously! Similar symptoms as you...radiator hot at the top, cold at the bottom...
Spongo wrote:Maybe the impellar is just spinning on the shaft?
had this happen on a 2.5 V8 once before, it took ages to work out why circulation was at standstill as the pump was in perfect working order before the rebuild.
And as per Simon's note, check radiator flow throughput. The radiator may have the volume req'd but if poor flow rate it's of no use. You mentioned the radiator's been re-cored/rebuilt, could you contact the radiator Co' and get the flow rate of 1. the core i.e. a Nissen unit and 2. measure the overall flow rate between i/p and o/p.
Quite common in the motor trade this one K series Rovers and 8 valve Golfs springs to mind steel or plastic impeller I have witnessed both but the give away is you always loose the heater for obvious reasons, it can also be intermittent, one Golf I did would randomly boil up sometimes it would go days before occurring randomly dislodging the impeller on the knurled shaft
Spongo wrote:Maybe the impellar is just spinning on the shaft?
had this happen on a 2.5 V8 once before, it took ages to work out why circulation was at standstill as the pump was in perfect working order before the rebuild.
And as per Simon's note, check radiator flow throughput. The radiator may have the volume req'd but if poor flow rate it's of no use. You mentioned the radiator's been re-cored/rebuilt, could you contact the radiator Co' and get the flow rate of 1. the core i.e. a Nissen unit and 2. measure the overall flow rate between i/p and o/p.
More common than you think. the K series Rovers and 8 valve Golfs springs to mind steel or plastic impeller I have witnessed both but the give away is you always loose the heater for obvious reasons, it can also be intermittent, one Golf I did would randomly boil up sometimes it would go days before occurring randomly dislodging the impeller on the knurled shaft
Il be honest. I really don't know where I'm at now.
The block seems fine. Brand new. Also checked tops of liners with straight edge when we removed heads for x-raying. Checked out ok.
Think I've discounted any blockage by being able to blow bubbles through the system from 1 bucket to another (see above post).
Think what il do now is check water-pump seeing as there was no flow. Even though it's brand new.
If the pump checks out ok (impeller not slipping and teeth oriented correct way) I will reassemble with new radiator, without thermostat, without header cap and use a "sniffer".
Other than that my dad is about ready to burn it!!!
Other thing with a one off installation like this is air locks forming, and or stop it being filled correctly. Most RV8s have cross flow rads - IIRC, yours is vertical? So might be worth adding one or more bleed valves to the likely points that air would collect?
I'd also add a filler to the top of the rad. You can buy the bits needed as plumbing in Screwfix, etc. And soldering to a brass header tank isn't difficult with a blow lamp.
Dave
London SW
Rover SD1 VDP EFI
MegaSquirt2 V3
EDIS8
Tech Edge 2Y
I am not really able to help but what timing cover do you have on the engine? If it is the later 4.0/4.6 cover without a dissy the the water pump turns counterclockwise when looked from the front where the earlier dissy V belt timing covers the water pump turns clockwise when looked from the front.
If the water pump is turning the wrong way eg old V belt system changed to a serpentine system or the newer serpentine changed to a V belt could be an issue.
I also have the header tank higher than the rest of the system. Despite that I needed a bleed line fron the top hose to the tank. The top hose runs upwards then downwards and I have bleed hose running from the topmost location to the header tank. I tried to run without it but the engine overheated due to airlock.
need4speed wrote:Regarding air locks, we have raised the header tank so it's highest point in the cooling system. That made no difference either.
That is only going to work as long as the highest point in the plumbing is connected to the header tank. As long as bubbles are able to collect somewhere, it isn't properly bled.
I am going to suggest that you remove the radiator, pump, 'stat and all lines for a good inspection for a blockage of some sort. Have a look in the heads, too if you can find a borescope because SOMETHING is impeding the flow of water through that engine.
These water pumps are not made to self prime. They are built way too loose. They will not suck water from a bucket when dry. They need to have a flooded suction to work.
So the bucket thing is a on starter. God Damn this problem is interesting and I would love to be able to come and play with it !!
perry
Perry Stephenson
MGB GT + Rover V8
9.62 @ 137.37mph
Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw
Back in the first post it states that your dad cut the end of the rad off and it appeared clear. Did he cut both end off? Have you actually run a hose through the rad to see if it flows well? I have known in one instance of a rad that got blocked by crud ejected from what was assumed a clean engine.
Also have you fed a hose through the engine? (With the stat removed of course)
As Perry said, Very interesting problem.
Regards Denis
1950 A40 Devon Hotrod with 5.0 twin turbo RV8.
EDIS8 wasted spark, Holley Injection.
Been as far as the Moon and back in 57 years of driving. Same Car, 5 engine upgrades !!!
mgbv8 wrote:God Damn this problem is interesting and I would love to be able to come and play with it !!
perry
Me too...although these type of faults are hugely irritating it's a great challenge to find and record the fault and get things up and running again.
Need4speed, where are you in the UK? We could muster the V8 troops, turn up en masse and have a group fault finding day. We wouldn't promise to fix the fault but would empty the house of tea and biscuits
Need4speed, where are you in the UK? We could muster the V8 troops, turn up en masse and have a group fault finding day. We wouldn't promise to fix the fault but would empty the house of tea and biscuits [/quote]
had this happen on a 2.5 V8 once before, it took ages to work out why circulation was at standstill as the pump was in perfect working order before the rebuild.
randomly dislodging the impeller on the knurled shaft 
