[Isdyl]

Hi, since SRH14914 is finally on the road now I figured I needed a new project and last week bought SRH15705 to get back on the road. The PO told me that she had 'cut out' and then refused to start, however after filling the empty radiator and discovering coolant pouring from a hole in the exhaust, I suspect they have possibly been a bit economical with the truth! Anyway, I wanted a project so a project I have. Today we removed the A bank head and discovered some damage as seen in the attached photo. The cylinder was full of coolant too, hence it had run into the exhaust. There also seems to be a bent valve on A4 for some reason and its unclear if this is related to the other damage. I am guessing that the engine over heated and the head lifted enough for combustion to burn through, but I wondered if anyone else has encountered this type of damage please? I'm going to need a replacement head, so I also wondered if I need one specific to a Shadow 1 or whether a Shadow 2 head will fit? Thanks, Dylan

 

[Dounraey]

Hi Dylan

It can be quite helpful to check out the parts manual to see if different part numbers are used for series 1 and 2 cars. The series 2 cars had extensive emission control features which may have impacted the head design for the later cars. Hopefully one of the professionals on this site may be able to help.

Catalogue

Buy genuine car parts for Heritage Bentley models (1955-2009) and Crewe-built Rolls-Royce models (1955-2002) at the official Bentley Motors heritage auto parts website.

heritage.bentleymotors.com

 

[AlanD]

If the tops of the two liners in the affected cylinders are damaged also it may need a new block??? It may be sensible to scrap the engine and buy a usable second-hand one.

Alan D.

 

[AlanD]

PS. That is SERIOUS damage. Has it been "hydrauliced" i.e. dropped into water with the engine running? The effect of the pistons trying to compress cylinders full of water might cause such damage and might overstress the con-rods. What else might cause it?

Alan D.

 

[Isdyl]

Hi - I'll give it a proper clean up and double check, but on first inspection the block and liners look undamaged. I'll post photos after cleaning. It would be a shame to change the engine as it's relatively low milage at 79,000 and has quite good history. Just 4 previous owners.

 

[Isdyl]

Hi - the part numbers for the head look the same - UE38445 - but I just wondered if anyone on here could confirm if a Shadow 2 head will fit on a '73 Shadow please?

 

[Wraithman]

Do not assume the block is ok. The liner bores in the very least must be measured. Use the workshop manual for guidance. I would also recommend new guides or very least new Posi valve stem seals going forward.

 

[Isdyl]

Thanks for the advise. At this stage I'm going to just fit new heads and hope for the best as the block looks ok. I just need to know if there is much or any difference between heads from later and earlier 6.75L engines please. I really don't want to start removing the block yet. Liners don't seem to have moved. Thanks, Dylan

 

[Dounraey]

You could try giving Flying Spares a call. They may have both in stock and could do a comparison.

 

[Isdyl]

Thats a good idea thanks.

 

[Wraithman]

FYI Liners do not have to move to be bad. Corrosion can squeeze liners out of round.

 

[Isdyl]

Ok thanks - I'll check and measure all I can, but really from the top it looks in reasonably good condition. The liners don't look in anyway damaged above the pistons - no scratches etc, and I don't think I should move the engine without the head in place incase I dislodge the liners. The liner seals are at the bottom? I think, so I'm not sure how I can check them? There's no water in the oil, so I guess there's a good seal round the pistons still as there was water in them.

 

[Jeff R 1]

You need a dial bore indicator to check things properly, the naked eye or by feel is no where near accurate enough to detect if the bore is out of round or tapered.
As a matter of fact, it's impossible with out measuring it with the proper tool.

Summit Racing SUM-900041 Summit Racing® Dial Bore Gauges | Summit Racing

 

[Isdyl]

Thanks for all your advise. The bottom line is though that this is a very low budget project and I don't have those tools. To be honest, I've literally just bought a head for £100 to see what happens. If it all goes wrong again I'll know there's an issue and I'll let you know either way. I'll also let you know if a Shadow 2 head fits on a Shadow 1 because so far no one on any of the forums I've asked has be able to confirm. The head gasket is the same though so I have my fingers crossed.

 

[Dounraey]

Dylan

I get where you're coming from and it could save you a few thousand pounds or prevent it from becoming a parts car (depending on the overall condition). Best of luck and fingers crossed.

Let us know how it turns out.

 

[Wraithman]

Go to the Bentley Heritage site and search for the head number on a Series I vs Series II same side. If they match you're on your way.

 

[Isdyl]

Hi - just thought I’d update you. The Shadow 2 head arrived and although there are a few casting differences it seems to fit and operate ok. Unfortunately when we refilled with coolant the other head started leaking from the gasket so that is clearly wrecked too! I’ve got the other S2 head and gasket now and we’ll fit it in the next week or so. The only small issue is that the head overheat sensor is a different thread size - larger hole on the S2 head, however I think it’s a bit worthless and will fit a temperature gauge I think in a different area.

 

[Wraithman]

There should be another hole, which may be untapped on the B bank.

 

[jeyjey]

But yeah, the overheat sensor is worthless anyway. By the time it goes off it's generally too late.

 

[Dounraey]

I agree with Jeyjey.

I fitted a temperature gauge on SRX18501 and it is the best mod I ever fitted. I found the best place for the temperature sensor was in the inlet manifold (which is coolant cooled). I removed the triangular plate, drilled and threaded it and fitted the sensor there.