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VT Losing Water, Drives OK though

Z2TT

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Hi Guys.

Just got a VT V6. Overflow bottle is filled with milky residue. Radiator Coolant is clean though
and Engine oil is perfect. Car does not smoke, starts fine and drives great.

Every few drives or so the radiator gets a little bit low on water, e.g not to the top but a little lower and always need to put a small bit in.

I'm wondering what the plan of attack should be. It seems to have no oil leaks around the Inlet manifold gasket so it must have been changed recently.

I'm thinking clean the overflow bottle out then see what happens.

Should I buy a Rad pressure tester and see if I can hear the leak or will a Leak-down test be better?

I'm thinking this engine has at some stage blown a head gasket and they did not clean the overflow bottle out.

Water Pump is new and can't spot any obvious leaks elsewhere.

Cheers.
 

Tree cutter

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The radiator cap might be faulty, causing it to suck in a bit of air into the radiator from around the seal on the radiator cap instead of sucking coolant back up from the overflow bottle. I would take the overflow bottle out and clean it with detergent. I think there are three bolts that you undo from underneath the bottle. The oil in the coolant has probably damaged the seal on the radiator cap.
 

umair

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Best way to clean the bottle is to use Oxiclean or oxygen powder. Put some water in the bottle and put some oxiclean and shake it up and leave it for two hours. After that rinse it and use a toothbrush or something flexible to wipe the residue out and it will be like brand new. I used a hanger attached to a cloth to wipe the grime out.
 

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The gasket can be rooted on the inside, like broken between the ports, same with the head gasket....the other thing is try to crank down the manifold bolts. They can become loose over time. If its losing water that's not a good sign.

You can get a mechanic to do some tests on the system to find the leak. Radiator pressure test wont tell you much unless theres a leak outside the engine. The mechanic can do a pressure test, by removing spark plug and using compressed air to see if any bubbles come out the radiator.
 

White VH SS

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The rad in vt on commodors can get a fracture on the plastic tank beside where the fan mounts to them and will leak small amounts but heat of rad evaporates the water and you won't notice
 

Z2TT

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Cheers for the Replies got me thinking lots of different causes.

I cleaned out the Overflow. The coolant in the radiator looks a bit to the brown side allthough no oil sludge in it.
unsure if it is just gunk accumulation over time or not.

About the rad cap pressure seal, if it were faulty and sucking in air, wouldn't it also be blowing out coolant to the atmosphere through the same seal and would notice it?

Cheers.
 

Tree cutter

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The radiator cap wont always leak outside where you can see it. My Calais was getting low coolant level in the radiator and the overflow bottle level was getting higher. There were no external leaks and a new cap fixed the problem.
 

umair

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Get an original cap, aftermarket do not last long.
 

Z2TT

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Hi Guys.

I've had no problems with Aftermarket Caps on Commodores Before, I always use CPC. I guess there are dodgy ones out there it's hard to find a good fit sometimes, That will be the next step if it's still losing coolant.

So i thought I'd start with a pressure test, Repco wanted $150 for a Pressure Test kit and I was unhappy that this car was costing me more money than it was earning, so I went on a mission to manufacture my own commodore cooling system pressure tester

So after some Trial and Error, mixing and matching I ended up with the following.

Ingredients :

1. Rubber Bushing with tappered bottom and hole in center
2. Tyre Valve
3. Two Rubber washers
4. Large Metal washer
5. 2 Cable Ties
6. Bike Pump
7. 2 Small Clamps
8. Bolt
9. Fuel hose

The Rubber bushing fit well on the filler cap, and because the sides were angled/tappered, you can apply pressure on it so it slides further into the filler hole and stays on. The bushing has a hole in the center which is where the bike valve will go.

The Two rubber washers were used to put under the bike valve so they can help seal the hole on the bush. and a washer was put on the pressurized side and attached to the bike valve, so to stop pressure from pushing it up, pretty much a way of securing the bike valve onto the bush so it cant detach with pressure.

The Overflow nipple was blocked off with a fuel hose and a bolt at the end, 2 clamps to secure.

Two Cable ties were used to secure the Bush to the filler neck incase pressure causes it to lift. The bike pump was attached to the valve and was pressurized. The pump is now removed and valve seals the coolant and I can now look for leaks, the leak was easily found and all at a low price.

The leak ended up being corrosion on the water pump inlet fitting under the coilpacks. Removed the hose and cleaned up
the corrosion with some sharp tools and made the surface nice and even. Back went the hose and filled up with AC Delco coolant and rainwater.

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