7.4L Big Block


Senior member
Jun 30, 2004
Cruising area
Kings Road

Finally got my boat in the water today and noticed two things:

I have water dripping into the Bilge from the Raw water pump. I will check this tomorrow with a small mirror to see if its coming from the hoses or the pump itself.

The other thing that i noticed is that it seems that coolent water is only exiting from the drivers side exhaust pipe and not the passenger side!!!

Any comments or ideas truly welcome.
Water exiting from one manifold only, is most likely just the simple non-return/thermostat relief valves within the thermostat housing.

This consists of a thin S/S rod which passes through the housing, on each end is a nut, a spring and then a nylon ball, this ball is held against the end of the casting where the hose to the manifold fits on.
The nylon balls are pushed off their seating by flow from the stat.

If one ball gets a bit stuck, or the water flow is weak at idle, you can sometimes get just one ball opening, which gives the symptom you're experiencing, at speed the flow to each exhaust is most likely fairly equal.

If you squeez the hose flat on the side which HAS got water exiting the tailpipe, you'll probably find water then coming out of the other side, and it's probable that when you release your clamp of the hose, the water will continue to exit from the side which was previously dry.
I think Matt had a similar problem with his balls once!!!:D
Thanks for that Johnson.

Ill investigate further tomorrow.:)
tony davis said:
I think Matt had a similar problem with his balls once!!!:D

..but in place of "squeezing his hose", a feckin' good kick should sort things out...
Jono said:
..but in place of "squeezing his hose", a feckin' good kick should sort things out...

I reckon Manning was right about you Nobba!:D :speechles
Cheers Matt.

I couldnt help noticing your boat at Drivers Wharf the other Day.

She sure looks the part.:D
Well ive had a look at the sea water pump using a small mirror and it appears that the housing has a hairline crack!

Must of frozen up during winter with some water still in her.

The local highwaymen wished to relieve me of £350.00 of her Majesty's finest for a new pump!! Feck i says, there £150.00 in the States M8.:mad:

So, i have ordered a new pump from the States but it will take some time to get here.

My question is, would you continue to use the boat in light of our summer having arrived or wait for the new part.

The current pump is only dripping very slowly and the engine temperature does not raise above 150deg.

What do you all think? :worthy:
You don't need a whole pump, The original bakerlite housing and cast iron endplate (with hose connections cast in) gets replaced with a plastic one piece jobbie! much better, and available from keypart as a sierra part, I have these on my boat.

Have a look at this
Thanks Guys,

New pump Cancelled, necessary parts ordered. :D

But should i still go out to play this weekend?
If the temp gauge says it's OK, just enjoy the weather.
Matt, yeah, I just googled sierra parts and listed that bit coz keyparts site is pants!

I bought the kit with housing, impellor, wear plate, etc, as you describe, can't remember the price, but 60 quid sounds ball park.

It's way better than the original shite with the cast iron end plate and gaskets also. (newer type is 'O' ringed housing)
that No rings a bell
OMG! does anyone have any razor blades I could borrow?

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