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Hepu water pump early failure

H

hessam69

Well-known member
Joined
Jun 19, 2009
Location
Sydney, Australia
So my 940 water pump started leaking from the bottom. It was fitted 2020, 18,000 kilometres ago.

Found no movement in the bearing. Removed it, and saw the impeller had contacted the housing and removed material. What seems to have happened is the shaft has moved inward, reducing the gap between the impeller. This caused friction, which generated heat, which blew the seal. I could also hear a screech sound upon engine shutdown.

I am now trying a GMB (made in Thailand) pump. Quite cheaper than Hepu pump too.
 
The Graff pumps are a good quality pump. I have heard of quite a few early failures of the Hepu pumps over the last 4-5 years. I know I replaced a very low miles Hepu pump 3-4 years ago. I think every manufacturer on the planet is dealing with quality issues these days. I have used countless GMB pumps without a single failure.
 
At one time we were using original Volvo water pumps on the pushrod engines assuming they were the highest quality. After the flange, pulley and fan came off and went into the radiator on a customer's car who was half way to Colorado and we had to pay for repairs we started using GMB water pumps exclusively and haven't had a problem since.
 
Didn't have problems with HEPU, I am on my second one now. First lasted over 60K miles and was only replaced because of the top O-ring leak. So far got about 70K miles on my second one installed over 3 years ago, the top O-ring starts to seep a little when cold.
 
I put in a cheapo unbranded water pump (with cast impeller) on the first timing belt I did on my 940 (it came with the car as spare when I bought it and it was an unbranded box) and it lasted without a single issue for more than 150,000 km's (yes, I might have slightly overshot the timing belt interval...).
I put a HEPU pump in last year when changing the belt, crossing fingers it holds that long again.
YMMV
 
PCH said:
Didn't have problems with HEPU, I am on my second one now. First lasted over 60K miles and was only replaced because of the top O-ring leak. So far got about 70K miles on my second one installed over 3 years ago, the top O-ring starts to seep a little when cold.
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That is usually where they leak, prematurely. I'm guessing it is the crappy surface finish. The Hepu I replaced somewhat recently leaked at the pump/head o-ring after ~ 20K miles. I expect a redblock water pump to last 150K miles just like the original pumps Volvo installed at the factory lasted. My Ford F250 7.5 V8 pump lasted 290,000 miles. The pump on my other 7.5 is at 175,000 miles and working fine. I'm going to replace it before this race season because changing one of those pumps is a 3-4 hour job. I'd hate to have to do it on the side of the road on a long haul trip.
 
I usually buy the Volvo gaskets and orings as I've had early failure of the Hepu oring on the head. But the pumps for me usually last about 75-80k miles with lots of local driving. I've also used the Gates pump which seemed decent for the money.
 
I don't trust the aftermarket o-rings. I always buy the Volvo ones, they don't harden as quickly which helps them stay reliably sealed.
 
dalek said:
Interesting. I've always thought the cast impellers were more efficient. I also had in my notes (from some thread here) saying that the NAPA TFW 42309 was a good aftermarket replacement. Looking at the pictures, it is a cast impeller one.
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The stamped impeller certainly isn't designed with fancy fluid modelling or anything... very simple design. if someone has a cast impeller pulled off the pump so you could get a good view of the geometry, you could make some assumptions about performance based on that.
 
dalek said:
Interesting. I've always thought the cast impellers were more efficient. I also had in my notes (from some thread here) saying that the NAPA TFW 42309 was a good aftermarket replacement. Looking at the pictures, it is a cast impeller one.
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Cast (full backed impellers) are wayyyy more efficient than a stamped one.
 
The rule of thumb in these pumps was a pressed impeller was a sign of a cheap pump that is not going to last. Cast ones have always been better

SKF have been great for me.

Another thing I have noticed with cheap pumps is they use smaller bearings
 
Harry Tuttle said:
Who cares about efficiency in a water pump? You have guys here complaining that the pump over-pressurized their cooling system and blew out the freeze plugs...:roll:
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Right. It's the most ridiculous thing I've ever heard. The impeller design makes ~ zero difference. If someone is going to turn the engine 8,000 RPM they probably want the cast impeller to reduce the possibility of cavitation. I have run more GMB pumps with their stamped impeller than any other make pump with absolutely Zero failures of the pump itself.
 
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