Carbon deposits(?) in cooling system

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Brenjacques
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Carbon deposits(?) in cooling system

Post by Brenjacques » Sun Apr 29, 2018 10:16 pm

I've been doing some work on the coupe, changing the sump gasket and fitting a new thermostat. I noticed when draining the coolant that it was pretty dark and when I removed the thermostat housing it was covered in a thin coating of carbon. I have noticed that it has ran with a (very slightly) steamy exhaust for a while. I'm thinking that the head gasket has a blow to the coolant but I'm not loosing any noticeable amount of coolant either. Is there anything else I should look out for before plunging into changing the head gasket? Oil is fine with no moisture ingress so I've got away pretty lucky with this one.

Bren

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MarinaCoupe
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Re: Carbon deposits(?) in cooling system

Post by MarinaCoupe » Sun Apr 29, 2018 10:42 pm

Sounds like the head gasket leaking between one or more cylinders and the water jacket.

If you are lucky it’s just the gasket, however it’s always best if removing the head to check the flatness of both the cylinder head and the top of the block, with a steel rule after removing all traces of the gasket and any sealant.

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Mon Apr 30, 2018 8:19 am

Thanks Chris, just what I was thinking! I'll get the engine stripped down and take a look. I'm just about to order a head gasket set, is there any particular kinds/brand I should avoid or are they all okay for the B series unit?

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Re: Carbon deposits(?) in cooling system

Post by MarinaCoupe » Mon Apr 30, 2018 7:32 pm

Go for a Payen gasket. They have rubber compression seals built in, which help to avoid future head gasket failure.

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Tue May 01, 2018 10:13 am

Got the Payen one on order, do you think it is worth changing the head studs too or will the current ones be fine?

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Re: Carbon deposits(?) in cooling system

Post by MarinaCoupe » Tue May 01, 2018 6:27 pm

Unlike modern car head bolts, which are designed to stretch when tightening and as a result can’t be re-used, A & B series engines use non-stretch studs screwed into the top of the block face, so they should be reusable.

However if a stud unscrews from the block when you take the head off, you should Loctite the stud back into the block before fitting the head.

If you want to replace the studs, you can use standard stuff from the usual suppliers, or you can get ARP studs.

When rebuilding the new Bemar (BMW Marina) engine in my Coupe, it uses the A series long studs. I bought some from a well known Mini spares (sic) supplier. Brian Viney described them as made of chocolate, so we bought some ARP once. Once again, you get what you pay for, don’t just decide based on price.

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balmy
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Re: Carbon deposits(?) in cooling system

Post by balmy » Tue May 01, 2018 10:25 pm

I’d replace them. They don’t cost much and have a habit of stretching and snapping. Seen it happen a few times.
1974 Marina Tc Coupe - Blaze - nicknamed THE PLOUGH!
1973 Marina Citron saloon TC - VERY rotten
1975 Jensen GT - shoddy but quick
2008 Ducati 1098R TB21 LE 200bhp/99lb/ft of a monster on two wheels. All from 1198cc
1998 Laverda 750 Formula-rare
1997 Ducati 916 Senna - appreciating in value nicely still
!974 Honda CD175-awaiting resto - now stripped

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Thu May 03, 2018 8:24 am

I think I will stick with the original studs for now then as they don't look in bad shape, I will run the nuts down them and see how they feel, if they are streched then I shall replace. Two of the studs freed with the nuts, how tight should I refit them? I have read finger tight and threadlock but equally it looks like people torque them too?

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Thu May 03, 2018 9:04 pm

Hi all
Been trying to remove the cylinder head but it is stuck on pretty bad. 4 of the head studs were seized in, luckily I managed to get three out but one is still very stuck. I've tried everything to try and free it and spent the last couple of days giving it plenty of oil. I tried two nuts but it eventually sheard the thread and then decided to weld the nut to the stud, both times I attempted it the weld broke. So there is one stud really stuck in the engine and no real way to get it out. The head is still on and will not free so I only have the final inch or so of the stud exposed. Any ideas what to do? Time is starting to get against me now as I only have until wednesday to have it back working before I am fully booked again which means I wont have the time to carry on with it.

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Re: Carbon deposits(?) in cooling system

Post by mickthefitter » Thu May 03, 2018 9:53 pm

What have you tried to free the head? I'm pretty sure when I took the head off the Marina I had in 1982, I just belted it side-to-side with a leather faced mallet to break the seal. But then the car was only seven years old at the time. I think I may have heard a suggestion about putting your spark plugs back and turning the engine over on the starter, in the hope the cylinder compression breaks the seal. Having said that, with the pushrods out, you need to know pistons aren't going to hit valves! I don't THINK the B Series is one of those engines, but I'm not sure. I need advice on that!

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Re: Carbon deposits(?) in cooling system

Post by MarinaCoupe » Thu May 03, 2018 10:41 pm

I have freed off a B series head by removing the rockers, leaving the plugs in and turning the engine over a few times and using the compression to pop the head off.

I have also heard, but not tried, removing the plugs, feeding soft rope like sash cord into each cylinder after removing the the rockers, then turning it over a few times.

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Thu May 03, 2018 10:48 pm

Hi Mick,
Yes I did the same, rubber mallet tapping it both sides but it is properly stuck on there, RH side is free and will start to lift but the left isn't budging. I read about studs corroding and locking onto the head which I think is the problem, especially with the one that is stuck on there now. I'm certain if the stud gets freed then the rest should be straightforward. I mean it is really stuck on there I just need to have a think of the next way to tackle it. I'm thinking heat and oil but I equally don't want to risk damage to the head or block.

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Re: Carbon deposits(?) in cooling system

Post by Brenjacques » Thu May 03, 2018 10:51 pm

Hi chris,

Thanks for the tip, I will give that a go tomorrow after work and see if I have any luck with it. Does anyone know what colour the head would have been from factory? It's been painted in a pretty bad red paint that is peeling, I'm going to give it a respray but would rather have it to the original factory colour.

Cheers!

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Re: Carbon deposits(?) in cooling system

Post by mickthefitter » Fri May 04, 2018 6:30 am

I think B Series of this era were black. I'm not sure what kind of oil you are using to try to penetrate the rusty stud. Many times I've heard, but never tried, putting diesel in stuck 'things' and letting it soak in. Its used for trying to free seized engines in the bores I think, but I guess that's because its still a fuel, so whether it works better than a proper penetrating oil like Plusgas, on a stud, I can't say. I do like Plusgas for seized threaded bolts better than multi purpose lubricants like WD40, but force is still required to break the seal. What I've thought about from my past life in maintenance engineering in factories (where often you aren't as delicate as you have to be with things like car engines) is you need some kind of shim or lever to try to work the head up the tight stud, but must not damage the block or head faces. I wonder if it were possible to get a tapered lever made of aluminium in the gap where the head is loose? But I have to say I've never tried anything like this on an engine! I've prised things apart on industrial machines where its perfectly fine to dress any burrs with a file, that's all!

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Re: Carbon deposits(?) in cooling system

Post by MarinaCoupe » Fri May 04, 2018 7:23 am

All B series engines in Marinas were painted black, both the head and block.

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