The V8 Owners Forum -

Evening all,
My P38 has a relinered block from Turners, which was done about 4 years ago.
A few weeks ago, I had a water leak from one of the core-plugs behind the flywheel. So I popped the transmission and changed it (presuming it was a bit of bad luck). Problem solved.

However I have a new leak, and when I investigate, the other one behind the flywheel is leaking (I guess it's that one), and two more on one side of the block.

Why on earth would I get so many core plug failures in such a short time? I've never had one fail before, and now 4 within one month of each other?

I have the fancy red OAT coolant in there (which to be fair is not precisely the right mix, but is most definitely pink).

Any ideas? (It's a bloody nuisance I can say that much!!)

Chris.

What is the mode of failure ?

Are the core plugs rotten ? broken ? holed ?

Or are you saying they are leaking around the edges where they should seal ?

ie perhaps they are not the correct size ? did you use any sealer ? were they installed correctly ? etc etc etc

Three appear to have holes, one appears to be around the outside.

They were all installed by Turner Engineering when they relinered the block, so I have no idea if they were top quality or not..... I would expect them to be good quality. I also expect they know how to replace them properly.....

I have ordered brass ones to replace them with.

It is very strange. At least I've had plenty of practice pulling the engine out!

Chris.

OAT antifreeze is said to attack quite a few metals used in older cooling systems. Modern cars that use it seem to have only aluminium and plastic parts. I'm fairly sure brass is one of the things it attacks too. Perhaps SS is ok?

I have OAT in my 90 and its had a couple of plugs go too recently. I rebuilt the engine in 2008 (I think) and new core plugs were fitted at the time.

I was suspecting the OAT so will be switching back to normal Blue coolant when I have swapped them all.

What are the core plugs made from ?

I thought they were normally plated steel ?

Very odd if they're corroding into holes that quickly !

The leaking core plugs are steel, plated with something unknown but a gold colour.

Anyone know what is in OAT?

Surely all engines have core-plugs, and they all seem to use OAT nowadays.

Does OAT have a finite life, after which it turns into some sort of strong acid? Or maybe it stops being anti-corrosive?

Chris.

I replaced my core plugs 2 1/2 years ago and am using OAT coolant. Haven't noticed a leak yet!
Mine were also zinc/gold plated.

Tom.

Did the very last Range Rover made with the RV8 use long life coolant? If so, did they have different core plugs?

The ones on my SD1 ain't yellow. Perhaps this is the new plating to resist that corrosion? Could it also need a special sealer?

I'm fairly certain brass is one the materials it does attack. Hence rads being ally and plastic these days.

Zinc yellow passivated

Reading this and other similar reports, I've decided to flush out my OAT (Organic Acid Technology) anti-freeze from my Rover with copper/brass radiator. & replace with 'normal' ethylene glycol stuff, Comma or Bluecol.

It's just in case, as I don't fancy pulling the engine out anytime soon just to replace core plugs.

Some pics:




Chris.

It does look like plain and simple corrosion...

Either the part was damaged during fitting, or they're crap quality parts and the plating has come off allowing it to corrode ?


Could anti-freeze really cause such corrosion ?

Given that warranty sticker etc on the plug...I'd be asking the builder of why they think it's happening with their parts ?

Now I am trying to find a suitable sealant to fit the new ones.
Loctite 540 seems to be unavailable (which is a pity as it looks perfect!)
Looking at Permatex Red Threadlocker now....

Chris.

surely any decent flange sealant would be fine ?

Loctite make quite a few., 574, 510, 518 kinda thing.