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Smokey

Post by MattA24 » Subscribing Member » Sun Dec 30, 2018 1:48 am
Joined: Wed Jan 15, 2014 9:06 pm
Posts: 213
Howdy,

As mentioned in another thread, I'm currently working on building a new box on the back of a '78 CF250 rescued from a north-wales hedge. Apart from that one big trip home, I've only been driving it occasionally back and forth to the workshop at the moment, so I haven't needed to investigate the engine yet, other than changing the cam belt for piece of mind.

The van runs sweetly enough, but it chucks out a fair amount of white smoke. I didn't notice the smoke on the long drive home from Wales, but that was in the dead of the night so I might have just missed it. I certainly notice it now, but I don't run the van often enough or for long enough to confidently say it isn't condensation-related. It's a fair old cloud though, so I'm suspecting other causes - does that mean a leaky head gasket (or cracked head/block) is the chief suspect?

Also, I don't think it's got hard valve seats fitted, as it had a half-bottle of Lead Replacement in the wardrobe. Owner of the hedge knew nothing about it's previous usage and abuseage.

So Question Time - Is there a good way to pin down the cause of the smoke? I'm going to try and do a compression test and check valve clearances soon anyhow. :?:

Something in the back of my brain whispers "head gasket". As it happens, the engine in my now permanently stationary parts van has hard valve seats fitted. If I do end up having to replace the head gasket in the hedge van, should I consider swapping in the parts van's hard valve seat head at this time? :?:

On another tack, but while I'm potentially ordering a bunch of gaskets online: I'm intending on changing the black block under the carburettor with one rattling around the parts box that has a little port fitted for a flashlube kit. Do I remember correctly that I need a pair of new gaskets if I disturb this block? :?:

Cheers!
Matt

Re: Smokey

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Post by VDUB384 » Club admin » Sun Dec 30, 2018 11:12 am
Joined: Wed Sep 12, 2012 9:01 am
Posts: 1415
If your talking a cloud of white smoke which doesn’t seem to clear I would suspect a cracked head although it could be a head gasket it’s definately getting plenty of water in the combustion chamber.
Dave
Whilst good maintainece is the best prevention"If its not broken don't fix it."
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Re: Smokey

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Post by Phil Bradshaw » Club admin » Sun Dec 30, 2018 4:25 pm
Joined: Sun Sep 02, 2012 7:15 pm
Posts: 3875
Smell of petrol and, or, exhaust fume in the top of the radiator usually is a clue for investigating further, e.g. pressurise cooling system with spark plugs removed to check for seepage into one or more cylinders - affected cylinder/s may spit out water mist (or more!) when the engine is cranked on the starter.

Leaky intake manifold to head gasket (either or both), or severe internal corrosion in the manifold between water passages and intake ports also can be a cause of water ingress into cylinders.

Carburettor insulator requires a gasket each side to seal.

Alternative tapping point is below the carburettor (used on earlier engines for a threaded adaptor for engine emission control).

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  • What is real is not the external form but the idea, the essence of things. Constantin Brâncuși

Re: Smokey

Post by MattA24 » Subscribing Member » Sun Dec 30, 2018 10:46 pm
Joined: Wed Jan 15, 2014 9:06 pm
Posts: 213
Hi Vdub & Phil,

Thanks for your replies. I'll take a good whiff in the top of the rad next time I give the motor a run, and report back (along with compression results when I get around to that).

Cheerio!
Matt

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