Black oil in expansion tank. XUD9TE.

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Deacon
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Black oil in expansion tank. XUD9TE.

Post by Deacon »

Hi guys,

Waaay back in 2013 I started seeing small drops of black oil appearing in the coolant. Didn't pay too much attention until 2018, when it became too apparent the oil in the coolant. So, I changed the original Modine oil cooler and flushed the system. Now again there's some black oil in the coolant. Went to the mechanic, stuck the expansion on top the coolant tank. Left the car running, then after lots of revving the only things that came up were some oil droplets.

So, I am guessing it's the head gasket then? Are there some near passages where low pressure oil could enter the coolant?

I mean, the engine is still rocking its original 20 y. o gasket so I guess it's time, I am just curious what's your opinion. Thanks.

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white exec
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Re: Black oil in expansion tank. XUD9TE.

Post by white exec »

On the XUD there is an O-ring in one corner of the head gasket that carries oil under pressure up to the camshaft and valve gear. Over time this can harden, and oil can weep into the nearby waterway.
Again, over time, XUD7 and XUD9 heads can gently warp, especially if subjected to overheating, or allowed to run with air pockets in them (as a result of insufficient bleeding).

With luck, a new HG will do it. Have the head checked for flatness before refitting it.

Deacon
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Joined: 31 Mar 2013, 16:57
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Re: Black oil in expansion tank. XUD9TE.

Post by Deacon »

Thanks for the info!

The appointment is set for May sometime then. The engine has never been opened and apart from two occasions when the temps got to 110 and 115 degr. C for a brief period of time, has never been above 85 degrees. Fingers crossed that the head is OK but even if they have to trim it, I think they have enough material left. Apart from that, I've put brand new radiator and hoses and will put only original parts and metal gaskets so the car will be set for the next what... 15 years or so lol. It will be a museum piece by then but blimey is that engine tough and worth keeping.

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white exec
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Re: Black oil in expansion tank. XUD9TE.

Post by white exec »

Sounds like a good plan, with an eye to doing everything properly.
They are extremely robust engines, if not overheated in the head department!