You'renottheonlyoneMaxine

Greetings from New Zealand!
I had the Valve Cover gaskets done on my '98 Maxine about 4-5 months ago and I've just checked the coolant to find that it's gone rusty.
I've searched high and low on the forums and discovered that to take off the inlet plenum, two little cooling hoses that cool the EGR valve have to be removed. Is it possible that in removing those and putting them back on after the job was done, air could have gotten into the cooling system and oxidized something in the engine?
Either way, the system will need flushing but I'd like to know if that's what caused it to maybe put my mind at ease.

Rit

iTrader: (3)

I highly doubt that adding some air to the cooling system would start the rusting process because I thought that antifreeze provides some corrosion protection. Unless your antifreeze was VERY old !

You'renottheonlyoneMaxine

Well, it's not new but it wouldn't be over three years old at absolute most. I just can't think of what would have caused it beyond that. I did read somewhere that air could cause oxidization but maybe they were wrong.

JvG

The engines in our North American Maxima uses an all-aluminum v 6 engine. The radiator is also aluminum. So rust is not an issue.

So I see that you live in NZ.

Is your engine a 4 cyl with an iron- block engine?

You'renottheonlyoneMaxine

Nope. It's a VQ30DE. Basically the same as the US spec as far as I can work out. Wouldn't the water pump be steel though? Also, the oil looks fine so I doubt it's head gasket failure.

JvG

A thought occurred to me. Perhaps the coolant has turned acidic for some reason.

It's possible , but unlikely to have a headgasket leak.

The exhaust gas in the coolant would cause the possible acidity and rust.

I worked on a 92 Toyota Cressida. Same engine as Supra. It had a blown gasket and was full of rust.

I'm thinking that one lump of something that rusts is the egr casting and perhaps cooler.

Does your car have cooling issues?

Another thought.... the water pump impeller has been known to rust as well.


These are just guesses on my part.

You'renottheonlyoneMaxine

It's only getting very slightly to warm when going uphill under a bit of load. Just cruising around it seems fine. And only the past two days, but because the coolant is really quite rusty, I'm thinking it's capacity for cooling is decreased. As logical as that suggestion sounds, I really hope it's not that....

JvG

Keep in mind that the radiator will also have rust inside it.

This rust condition is rare on this forum.

I'd like you to attach a plastic bag to the neck of the radiator with painters tape. Make sure the tape seal is airtight.

Make the bag at least 40cm x 40 cm.

Run the car till it's warm.

Leaking exhaust gas would fill the bag.

I doubt that this is your problem, but should be considered before investing money on repairs.

You'renottheonlyoneMaxine

Unfortunately I don't have a bag or tape to do that and it'll have to be flushed out anyway so I'll take it down to our local garage (who's very good) and see what they say. Maybe it is just old coolant. Here's hoping!

JvG

I'm in Oregon, on the west coast of the usa.
The wet Part of the Pacific Northwest looks a lot like your South Island, or so we are told.

schmellyfart

iTrader: (46)

JVG even though the block and radiator are aluminum, the water pipes and water pump are steel and can rust if the coolant system isn't serviced regularly.

To answer OP's question, yes that can introduce an air pocket to the cooling system. But not that's not going to be the cause of your rusty coolant in 5 months.
Rule of thumb is to drain/fill your coolant system every 2 years at minimum. The corrosion inhibitors in you coolant only last so long.

You'renottheonlyoneMaxine

Well, we got the system flushed out and it's been good until just now when I went to check it and guess what? It's rusty again! So, is it more likely to be a gasket problem leaking exhaust gases into the coolant and wrecking it that way? Or is something rusting inside, like the pump/hose fittings? Or is this just how modern coolant is?

schmellyfart

iTrader: (46)

If you have some parts rusting within the cooling system, flushing the coolant isn't going to stop the rust.