madbrit

madbrit

Active Member
My V8 p38 petrol 51 plate started overheating for no apparent reason, I had the block tested with the blue solution, no leak into cooling system detected, so I changed the pump, old one was ok changed the thermostat, changed the expansion cap, changed the Viscous unit, all to no effect, still overheating, so I thinking the new thermostat not working, so got old one, bodged it so water flows through anyway permanently, still overheating, I did get rid of any air locks by taking off the top hose, heaters are working.
I am now at a complete loss, any ideas anyone ? only thing I have not done is change the rad ;(
 
Sounds like your radiator is blocked internally or externally then! It doesn't take much.
If you bodge your thermostat, then you will always have flow through the radiator and you'll never reach operating temperature
 
yes that next is the next job Monday, pump water into the top, see what flow at the bottom, I presume that is the way, might just order another one anyway.
 
madbrit said:
yes that next is the next job Monday, pump water into the top, see what flow at the bottom, I presume that is the way, might just order another one anyway.
Click to expand...
It may be blocked between the fins so take it off and have a proper look. There was someone a couple of weeks ago who thought their rad was clear until he took it off,a search (top right of page) may bring his post up.;)
 
madbrit said:
My V8 p38 petrol 51 plate started overheating for no apparent reason, I had the block tested with the blue solution, no leak into cooling system detected, so I changed the pump, old one was ok changed the thermostat, changed the expansion cap, changed the Viscous unit, all to no effect, still overheating, so I thinking the new thermostat not working, so got old one, bodged it so water flows through anyway permanently, still overheating, I did get rid of any air locks by taking off the top hose, heaters are working.
I am now at a complete loss, any ideas anyone ? only thing I have not done is change the rad ;(
Click to expand...

So what are the signs showing u have of the engine overheating?
The water pump doesn’t cause overheating unless the impeller has somehow detached , you hear that, thermostats can fail but usually open, the viscous unit is easy to test, the sound of it would give it away if faulty when starting up.
Was the coolant blowing from the expansion cap, is the top hose hard with the high pressure. ??
With the rad… try flushing, best way is a reverse flow, but a bit of an involved job removing the rad if yours incorporates the oil coolers.
 
If the rad is the same as a diesel one ,theres a baffle in the top that forces water down one side n up the other side ,if its failed then water just flows across the top ,,check the rad for heat at the bottom should be hotter at one side n cooler at the other , a scope and torch or marble test :eek:;);)
 
dubbleRR said:
If the rad is the same as a diesel one ,theres a baffle in the top that forces water down one side n up the other side ,if its failed then water just flows across the top ,,check the rad for heat at the bottom should be hotter at one side n cooler at the other , a scope and torch or marble test :eek:;);)
Click to expand...
its not the same as the diesel one.
The test I did on mine, place radiator on a flat surface, fill with hot water from a kettle as quickly as possible, then use IR thermometer to look for any hot/cold spots
 
  • Flush the whole system, not just the rad.
  • Is it losing coolant or just overheating ? Any leaks will prevent the system getting proper pressure, and it will boil.
  • Check the un-obvious like core plugs, underneath throttle body heater, etc.
  • Also do a pressure test when the engine is warmed up, and not running so you can see any leaks.
Air locks should be sorted by following the RAVE procedure rather than the top hose.
 
pwood999 said:
  • Flush the whole system, not just the rad.
  • Is it losing coolant or just overheating ? Any leaks will prevent the system getting proper pressure, and it will boil.
  • Check the un-obvious like core plugs, underneath throttle body heater, etc.
  • Also do a pressure test when the engine is warmed up, and not running so you can see any leaks.
Air locks should be sorted by following the RAVE procedure rather than the top hose.
Click to expand...

And is the internal footwell carpet wet ? With coolant ...
 
If none of the above, a compression check on each cylinder with the Throttle wide open for any differences between cylinders.
Pull your rad out also and look for dead leaves mouse nests and dead birds jammed up in there reducing air flow. As said above. ;)
 
Mark Piercy said:
If none of the above, a compression check on each cylinder with the Throttle wide open for any differences between cylinders.
Pull your rad out also and look for dead leaves mouse nests and dead birds jammed up in there reducing air flow. As said above. ;)
Click to expand...

Dead birds? Sure you don't mean peasants?
 
tomcat59alan said:
My neighbour thought he'd hit a pheasant a couple of days ago,he stopped but couldn't find it, when he got home he as a proper look and found it had been forced through the plastic grill ( Honda) and was against the radiator. His wife wouldn't entertain eating it????.:eek::rolleyes:
Click to expand...
isn't there some daft law that says you can pick up roadkill, but not if you hit it? o_O
 
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