Rover P6 2000TC - exciting* video action

[N Dentressangle]

11 minutes ago, SiC said:

Yeah I agree performance isn't exactly an important point but thinking more that it could make it run rougher given an incomplete burn on that cylinder. Especially sharp edges that get hotter than others, potentially cause pre-combustion?

Possibly.

I'll tidy it up as best I can with the die grinder - getting hold of a good s/h one will be tricky. Modern fuels also seem far better in that respect: I couldn't make it pink before no matter what I did.

[N Dentressangle]

On 09/05/2025 at 14:31, comfortablynumb said:

Can't really see on the photo, but how's the bore?

I think the tapping noise I could hear was probably piston slap. That would fit with it getting quieter when hot, too.

Have a look at the bore and piston skirt and tell me I'm wrong?

[Matty]

I think seeing as you have the ability and facilities (unintentional poem) there's no harm in radiusing the edges of the damage, doing a nice job of putting it together and seeing how you go. Obvs sharp edges will draw heat and create hot spots. I'm only a fitter and make no claim to be the next Brunel but in my head any sharp edges like that on a piston crown would draw heat and maybe result in pre ignition. No harm in dressing them up nice and having a go at it as long as you don't mind pulling it in bits again?

[N Dentressangle]

2 minutes ago, Matty said:

I think seeing as you have the ability and facilities (unintentional poem) there's no harm in radiusing the edges of the damage, doing a nice job of putting it together and seeing how you go. Obvs sharp edges will draw heat and create hot spots. I'm only a fitter and make no claim to be the next Brunel but in my head any sharp edges like that on a piston crown would draw heat and maybe result in pre ignition. No harm in dressing them up nice and having a go at it as long as you don't mind pulling it in bits again?

That's how I see it too.

Plus it wasn't causing any issues before, so should be OK again I reckon.

The trouble with these things is knowing where to draw the line. Even doing a basic job on this engine would run to £500+, and then where do you stop? There's always more you could do in terms of rebuilding and refreshing things, and parts such as bearings & piston rings for these lumps are really dear compared with something common like an A series or RV8. If it were a BMW 2002 or something worth £££ then again you might think it was worth it, but sadly these aren't valuable cars, especially the 4cyl ones, and it just makes no sense to spend what you don't have to. If it'll go back together and be good enough for pottering about, that'll do me.

[Bmwdumptruck]

Have you had a look around to see if a piston is obtainable? While it’s apart I think I’d have a good look.  As you say it’s quite likely piston slap looking at the marks on the sides of the skirt.  Would be worth at least trying to mend known issues before reassembling wouldn’t it?  Not like you have to have it back running to get to work monday is it? 

[tooSavvy]

12 minutes ago, Bmwdumptruck said:

Have you had a look around to see if a piston is obtainable? While it’s apart I think I’d have a good look.  As you say it’s quite likely piston slap looking at the marks on the sides of the skirt.  Would be worth at least trying to mend known issues before reassembling wouldn’t it?  Not like you have to have it back running to get to work monday is it? 

This article/thread concerned 'knurling' the piston, using a dedicated machine ('40s/'50s)..

.... this is another avenue 🤔

🚙💨

[N Dentressangle]

4 minutes ago, tooSavvy said:

This article/thread concerned 'knurling' the piston, using a dedicated machine ('40s/'50s)..

.... this is another avenue 🤔

🚙💨

Wow

Not sure I'm brave enough to try that 🤣

[MikeR]

4 minutes ago, tooSavvy said:

This article/thread concerned 'knurling' the piston, using a dedicated machine ('40s/'50s)..

.... this is another avenue 🤔

🚙💨

I remember seeing an article about a piston that was found with punch marks around the skirts , it was considered another method of stopping piston slap .

imho opinion they are not exactly small pistons or cutaway so they could just be cleaned up , seen a lot worse in a 2 stroke and they still worked ...chances are it will sound bad until it gums up again ...

 

[Momentary Lapse Of Reason]

How much is a new piston with rings in that size ?

Piston knurling required a dedicated machine - who has one of those theses days?

(and it was a botch anyway).

If the new piston and rings is not too expensive, blaze bust the bore with a hone, fit the rings properly inc. gaps.

(Proceed to point B )

If the new piston and rings is too expensive / not available,

then polish the bore first, (back of emery cloth and oil) then the lightest hone you can get away with.

Clean (not linish) the piston skirt.

(Point B )

Blend the damage to the piston head.

Check that the valves are seating OK.

Set valve gaps.

Put back together and enjoy.

Edited May 10 by Momentary Lapse Of Reason
Fecking smilies

[Dj_efk]

Back in the day you could get slightly oversize piston rings. Wonder if you still can?!

[danthecapriman]

Just my opinion, but I’d grind that piston and reuse it if you can’t get one to replace it. It’s not (seemingly) cracked or holed and it was working ok before. Just give it a gentle grind to get rid of any hard edges and it should be fine.

Regarding the other stuff. It depends on what you can afford and what you want to do with the car. 
If it was a daily driver and did a bit of mileage then doing the lot would most likely be the best option. 
If you just use it on a weekend for a bit of pottering about/fun then do what you absolutely need to and no more. In that sort of use it’ll probably go for years yet before problems start surfacing. 
You could also consider doing the bare minimum on this engine to get it usable again but in the meantime keep an eye out for a better engine to rebuild for it over time. That way you can still use the car and build an engine for it to use later once it’s done.

Fwiw, the damage to that piston isn’t the worst I’ve seen! 
When I was working in a garage we had something (I forget what now!) but it was something like a zetec engined Mondeo of Focus. It had somehow ingested a washer and was running badly. 
On taking it to bits, we found one of the valves was bent and the washer in the same cylinder had been stamped into the piston but at more of an angle so it was literally stabbed into the piston. 
The owner wouldn’t pay for repairs or replacement of the engine fully and told us to do only the valve and see what happened. 
It ran fine after the bent valve was replaced and the remains of the washer were pulled out of the piston. I don’t know how long it lasted as I never saw the car again but it worked!
 

[N Dentressangle]

4 minutes ago, Momentary Lapse Of Reason said:

How much is a new piston with rings in that size ?

Piston knurling required a dedicated machine - who has one of those theses days?

(and it was a botch anyway).

If the new piston and rings is not too expensive, blaze bust the bore with a hone, fit the rings properly inc. gaps.

(Proceed to point

If the new piston and rings is too expensive / not available,

then polish the bore first, (back of emery cloth and oil) then the lightest hone you can get away with.

Clean (not linish) the piston skirt.

(Point

Blend the damage to the piston head.

Check that the valves are seating OK.

Set valve gaps.

Put back together and enjoy.

I'm liking that approach. It will be plan B, as pistons and rings are £££ for these engines.

I've ordered a bore honer so will try and build things back up this week.

[jonathan_dyane]

It's hard to see from the photo but the bores look like they need a rebore, I suspect if you hone it until you get them smooth you will have taken too much off.

Also the piston rings look scored to fuck although again hard to see without being able to inspect on person/feel

[N Dentressangle]

12 hours ago, jonathan_dyane said:

It's hard to see from the photo but the bores look like they need a rebore, I suspect if you hone it until you get them smooth you will have taken too much off.

Also the piston rings look scored to fuck although again hard to see without being able to inspect on person/feel

In an ideal world you'd drop £1k+ on rebuilding this engine.

But we're going for pragmatism. I'll put it back together as well as I can, without throwing good money after bad, and see how it runs. I have a lead on a spare engine too, if it comes to that.

[Surface Rust]

I'm sure you've had a look, but is the underside of the crown OK and crack free?

Had an engine drop a valve once at work, it was neatly embedded in the piston like it was one piece, but the underside of the crown looked like a dried up river bed.

[artdjones]

Do you know anyone that does aluminium welding? Fill up the damage with weld then die grind back flat.

[N Dentressangle]

Had a few errands to run in the sunshine today, so decided to use the most appropriate vehicle:

She started OK after two years sitting in the barn. Put some air in the tyres, brushed off the cobwebs and cleaned the windscreen, and headed down to the local engineering shop with the P6 valve shims:

I measured the clearances (or lack of them) before stripping things down, so I've left them with instructions on how much to grind off each shim.

Slow re-assembly will begin tomorrow, I hope.

[High Jetter]

1 hour ago, N Dentressangle said:

Had a few errands to run in the sunshine today, so decided to use the most appropriate vehicle:

She started OK after two years sitting in the barn. Put some air in the tyres, brushed off the cobwebs and cleaned the windscreen, and headed down to the local engineering shop with the P6 valve shims:

I measured the clearances (or lack of them) before stripping things down, so I've left them with instructions on how much to grind off each shim.

Slow re-assembly will begin tomorrow, I hope.

Just noticed your Series has a Brighton reg - do you know the original dealer? We used to keep boxes of different thickness shims at the Jag/Rover/Triumph dealer I worked in parts for, hope they'll be ground accurately.

[N Dentressangle]

44 minutes ago, High Jetter said:

Just noticed your Series has a Brighton reg - do you know the original dealer? We used to keep boxes of different thickness shims at the Jag/Rover/Triumph dealer I worked in parts for, hope they'll be ground accurately.

It's not the original plate - the original one was sold in about 1981 and went onto a long since scrapped Bova Futura I believe.

[N Dentressangle]

So, the slow rebuild continues.

I used the die grinder to reshape the top of the damaged piston as best I could, and re-fitted it:

Cleaned and honed the bore too, as you can see.

As I was using the piston ring compressor to get this one in, the cause of this engine's problems finally came to me.

It's been staring me in the face. This is probably the filthiest engine internally I have ever worked on. And for one exhibiting very little bore wear, it has tons of blow by. The fresh oil I put in, after 80 miles looks like it's done 5000. And the piston I replaced, when it came out, had stuck rings. After cleaning with loads of brake cleaner the rings were springy and moving like they definitely weren't before.

The rings are gummed up. It's causing low compression and blow-by, leading to piston slap and an ever filthier engine.

It's the only diagnosis which makes sense. And would also mean that a warmer engine would be quieter, which couldn't be said of bearing wear.

The sump is now back on, so no way I'm undoing a million bolts again and pushing out the three other pistons. My plan is to fill the 3 cylinders not yet free with a mix of ATF and paraffin and leave overnight. I can then drain what falls through out of the sump (it's still empty) and repeat. The soaking begins now!

That's the plan, anyway 😎

[Matty]

2 hours ago, N Dentressangle said:

So, the slow rebuild continues.

I used the die grinder to reshape the top of the damaged piston as best I could, and re-fitted it:

Cleaned and honed the bore too, as you can see.

As I was using the piston ring compressor to get this one in, the cause of this engine's problems finally came to me.

It's been staring me in the face. This is probably the filthiest engine internally I have ever worked on. And for one exhibiting very little bore wear, it has tons of blow by. The fresh oil I put in, after 80 miles looks like it's done 5000. And the piston I replaced, when it came out, had stuck rings. After cleaning with loads of brake cleaner the rings were springy and moving like they definitely weren't before.

The rings are gummed up. It's causing low compression and blow-by, leading to piston slap and an ever filthier engine.

It's the only diagnosis which makes sense. And would also mean that a warmer engine would be quieter, which couldn't be said of bearing wear.

The sump is now back on, so no way I'm undoing a million bolts again and pushing out the three other pistons. My plan is to fill the 3 cylinders not yet free with a mix of ATF and paraffin and leave overnight. I can then drain what falls through out of the sump (it's still empty) and repeat. The soaking begins now!

That's the plan, anyway 😎

Makes a world of sense tbf. Good plan and can't see why it won't glean positive results. Best of luck kid 👍 

[N Dentressangle]

An overnight soak and it's all drained through:

Time to jiggle the pistons a bit and repeat

[jonathan_dyane]

Piston looks good and the bore has cleaned up better than I expected which is great.

You should be able to feel the level of piston slap and so whether the rings have unstuck using your thumbs on the piston top now you have a 'good' piston to compare with 

[N Dentressangle]

Interesting now to watch the relative speed of the ATF / paraffin potion drain through the cylinders. Remember the compressions?

1 - 145

2 - 135

3 - 150

4 - 140

Predictably, #2 is draining easily the fastest. #4 is in second place, with #1 not losing much at all.

Ideally we'd be seeing 190psi across the board, as this is a 10:1 CR engine, so something's clearly amiss. And as the bores aren't tragically worn...

Going to top up again now and add some brake cleaner to the potion, and pour some in #3 as well to act as a control.

[N Dentressangle]

Third lot of potion added:

Plan is to add one last dose when this has all drained through and leave overnight.

The machined valve shims have come back from the engineering shop.

Re-assembly tomorrow, and I can re-check the valve clearances and have the shims quickly adjusted again on Mon am if needed, as the machine will still be all set up for the job.

[N Dentressangle]

#2 is now holding up well, and #1 is in the lead!

[N Dentressangle]

All the potion had drained through this morning so I emptied it out of the sump and got on with the job.

I've used a few pints of Jizer on this engine, and it's probably the best degreaser I've found. A good brush on, then hose off. The weather's been good for drying stuff too:

I don't think I've actually ever rebuilt an OHC engine before (new fangled technology if you ask me - never catch on) so I was fairly slow and cautious about how things went back together.

Blasted all the threads in the block with brake clean then the airline - more black gunge removed, so glad I did that. Gave the head a final polish, and re-fitted it with the cam carrier:

The greenish stuff you can see is assembly lube. Plain oil is fine, but a squeezy bottle of Lucas Assembly Lube just makes life a bit easier.

As you can see, I've already fitted the tappets and newly machined shims here (underneath them - they sit directly on top of the valve stem). Let's hope I got all my sums right when I asked for metal to be shaved off!

Cam fitted next, and very slowly and carefully torqued down. The cam bolts are also the head bolts, so this bit has to be right. I took things in stages, and followed exactly the order in Haynes, and finally we got there:

The thermostat housing on the right has also been removed - a struggle, but it saw my point of view eventually - cleaned up and replaced along with a new thermostat.

OK, moment of truth - time to check the valve clearances. Here's what we're aiming for:

and the left hand column is where we've ended up:

Get in!!!!!

I was aiming for them to be towards the top of the tolerance rather than tight. It's likely they'll get tighter if anything, and loose valve clearances are always better for an engine than tight ones, like it had before.

Very happy with that.

So here's where we are now:

Re-fitting the timing chain tensioner was a bit of a fiddle but manageable. Nearly dropped a telescopic magnet thing down into the sump - oh how I chuckled 😉

Exhaust and carbs yet to re-fit, plus the gubbins around the front of the engine.

Onwards!

[tooSavvy]

My IMP cam carrier/caps were NOT part of the Head assembly = Head bolts were UNDER the cam carrier [A special tool.. U- shaped nut driver.. needed to retorque bolts after running] and that meant shagging on with cam/shim gaps was *less of a fu#k on...

You have to build/torque the gasket down BEFORE you know you're set right... 😮 Bloody Hell

🚙💨

[N Dentressangle]

28 minutes ago, tooSavvy said:

My IMP cam carrier/caps were NOT part of the Head assembly = Head bolts were UNDER the cam carrier [A special tool.. U- shaped nut driver.. needed to retorque bolts after running] and that meant shagging on with cam/shim gaps was *less of a fu#k on...

You have to build/torque the gasket down BEFORE you know you're set right... 😮 Bloody Hell

🚙💨

Yup. A real PITA of a design.

Really glad I got the clearances right first time!

[N Dentressangle]

And just by way of contrast, this is the filth things were running in before:

Minging. And this oil was 80 miles old!