Brakes mystery

Datatek · Jul 16, 2014

StuckAgainSteve said:
Yes the cooling system was marginal - as soon as you got furred up waterways (from lack of antifreeze) they would overheat the airflow through the rear mounted rad also stalled at about 55 mph. The water pumps usually failed because they were stored incorrectly (face down) - yes that's how delicate they were! Such a shame because the Imp engine and transaxle were superb.

In my experience, the pumps failed because there was no protection on the front facing bearing, I modified several and there were no failures afterwards. I also fitted one of mine with an electric pump.

wammers · Jul 16, 2014

Datatek said:
Imp engine came from a Coventry Climax fire pump. Good engine let down by the water pump and cooling system. Never a problem in the fire pumps.

Fire pump engine was a scaled down Coventry climax racing engine. Spec was it had to be two man portable. Imp engine was a good unit but quite obviously all the ancillaries were bolt on after thoughts. That is always the impression it gave me anyway.

bmp42 · Jul 16, 2014

The Imp was a much maligned car, most of its cooling problems where caused by its failure to obtain type approval - the side lights where too low, so with the tooling already in place the easy solution was to fit longer front springs and shocks to achieve the correct height for approval - this had the knock on effect of the aerodynamics around the rear engine cover air intakes being outside the designed airflow to feed the fan enough air so at speed on dual carraigeways a negative air pressure was caused by the fan not pulling enough air through the engine cover and the air outlet on the back of the fan having air forced up it. Yes the seals and bearings that where used to build the water pumps where not very good at the time so they failed, that then created another problem as workshops at that time did not have accurate enough torque wrenches to tighten the headbolts correctly. The bleeding of the cooling system was also a bit of a faff to do correctly and not many people knew how to do it succesfully, with air in the system it caused the water pump impelor to cavitate in the coolant so not circulating the coolant correctly.How do I know - I used to build them for racing and rallying plus competed myself back in the days when the world was in black and white !!

wammers · Jul 16, 2014

bmp42 said:
The Imp was a much maligned car, most of its cooling problems where caused by its failure to obtain type approval - the side lights where too low, so with the tooling already in place the easy solution was to fit longer front springs and shocks to achieve the correct height for approval - this had the knock on effect of the aerodynamics around the rear engine cover air intakes being outside the designed airflow to feed the fan enough air so at speed on dual carraigeways a negative air pressure was caused by the fan not pulling enough air through the engine cover and the air outlet on the back of the fan having air forced up it. Yes the seals and bearings that where used to build the water pumps where not very good at the time so they failed, that then created another problem as workshops at that time did not have accurate enough torque wrenches to tighten the headbolts correctly. The bleeding of the cooling system was also a bit of a faff to do correctly and not many people knew how to do it succesfully, with air in the system it caused the water pump impelor to cavitate in the coolant so not circulating the coolant correctly.How do I know - I used to build them for racing and rallying plus competed myself back in the days when the world was in black and white !!

The torque wrench talk is nonsense accurate torque wrenches have always been available. Maybe some didn't use them but that's a different story. The front end was lifted for export reasons.

Datatek · Jul 16, 2014

bmp42 said:
The Imp was a much maligned car, most of its cooling problems where caused by its failure to obtain type approval - the side lights where too low, so with the tooling already in place the easy solution was to fit longer front springs and shocks to achieve the correct height for approval - this had the knock on effect of the aerodynamics around the rear engine cover air intakes being outside the designed airflow to feed the fan enough air so at speed on dual carraigeways a negative air pressure was caused by the fan not pulling enough air through the engine cover and the air outlet on the back of the fan having air forced up it. Yes the seals and bearings that where used to build the water pumps where not very good at the time so they failed, that then created another problem as workshops at that time did not have accurate enough torque wrenches to tighten the headbolts correctly. The bleeding of the cooling system was also a bit of a faff to do correctly and not many people knew how to do it succesfully, with air in the system it caused the water pump impelor to cavitate in the coolant so not circulating the coolant correctly.How do I know - I used to build them for racing and rallying plus competed myself back in the days when the world was in black and white !!

No torque wrench will compensate for a head warped by an overheat caused by pump failure. I too used to race them with friends.

Grrrrrr · Jul 16, 2014

cheongthong said:
read here :fighting:Please read all P38 owners up to mid 1999(brake modulators)

maybe you can order from this guy [email protected]

Thanks. I have seen this before. Odd that mine is 19 years old with no sign of this and presumably still plastic inside. Problem is any rubber seals inside, I suspect. Quite an expensive "fix".

All a bit moot at the moment because the seller has pulled out saying wrong stock. I suspect selling a unit for £4 may be the real reason. There's a box for a reserve amount, use it! I don't mind blowing a fiver for a unit to strip it but I'm not paying £50! Grrrrrr.

Brakes mystery

Datatek

Well-Known Member

wammers

No longer with us, RIP

bmp42

Active Member

wammers

No longer with us, RIP

Datatek

Well-Known Member

Grrrrrr

Technician, Bodgit & Scarper Ltd

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