Compression Test results

[Arbman Al]

Hi All,

Here are the results of my compression test. Only done once without adding a drop of oil yet as battery was dying down:

Cylinder No.1 85 psi

Cylinder No.3 120psi

Cylinder No.5 0 psi :shock:

Cylinder No.7155 psi

Cylinder No.2 110 psi :?

Cylinder No.4 130 psi

Cylinder No.6 95 psi

Cylinder No.8 70 psi

Expert analysis welcome!

TIA......Al.

[Kevin Garrod]

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Not an expert analysis but I'd lay odds that you will be taking the heads off next!

[mad cyclist]

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it cannot get any worse but could get a whole lot better if you start it up, if its knacked time for a rebuild any way!!

you sure on no 5 your tester was screwed in all the way

rgds nick the optomist

[Arbman Al]

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mad cyclist wrote:

it cannot get any worse but could get a whole lot better if you start it up, if its knacked time for a rebuild any way!!

you sure on no 5 your tester was screwed in all the way

rgds nick the optomist

Yes Nick, I double checked it as well and it was still '0'.

I am guessing the valves are stuck open?

All the bits arrived today to service carbs, water pump etc and also inlet manifold gaskets. Will sort those bits out and then try to start it again to get some heat into the old girl, unless the master technicians advise otherwise!

Al the ETERNAL optimist

[John]

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Whip off the cam cover and see if a valve is stuck. If it's open significantly, I'd have thought you could hear it colliding with the piston. Continuing the optimism theme, if just a little stuck, it might free up when it's running - you never know.

[GDPR]

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If this engine hasn't run for some years but was OK when it last ran then you need to free some things off - No5 is almost certainly a stuck valve - whip off the RH cam cover turn the engine over so the cams aren't lifting the valves and give the buckets a sharp tap downwards with a smallish hammer and a drift that won't damage the bucket - this should unstick the valves.


You should go and buy a litre of diesel and put 50 ml down each plug hole - if you can remove the inlet manifold and stick the diesel down the inlet port instead of the plug hole, even better - this will positively lube the inlet stems. Leave for an hour or so, spin the engine over on the key, and then put another25 ml down and leave to soak overnight. The first lot will coat the valves and the diesel should creep and lube dry/rusty stems, and the second lot is to help free off any stuck piston rings. If this works, then your compression test should be much improved, but this engine will smoke like a ******* for the first few minutes of running:shock:

If that doesn't help, you may have to pull the heads off and have a ferret about.

[Arbman Al]

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kryten wrote:

If this engine hasn't run for some years but was OK when it last ran then you need to free some things off - No5 is almost certainly a stuck valve - whip off the RH cam cover turn the engine over so the cams aren't lifting the valves and give the buckets a sharp tap downwards with a smallish hammer and a drift that won't damage the bucket - this should unstick the valves.


You should go and buy a litre of diesel and put 50 ml down each plug hole - if you can remove the inlet manifold and stick the diesel down the inlet port instead of the plug hole, even better - this will positively lube the inlet stems. Leave for an hour or so, spin the engine over on the key, and then put another 25 ml down and leave to soak overnight. The first  lot will coat the valves and the diesel should creep and lube dry/rusty stems, and the
second lot is to help free off any stuck piston rings. If this works, then your
compression test should be much improved, but this engine will smoke like a ******* for the first few minutes of running:shock:

Thanks for that Russ. For the benefit of the forum users I won't PM you about this saga, as it may be a useful archive for some other poor soul in the future.

Do the plugs go back in prior to turning over the engine?

Rgds......Al

Do the plugs go back

If that doesn't help, you may have to pull the heads off and have a ferret about.

[GDPR]

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Plugs stay out in case of hydraulic lock - you wouldn't want to bend a con-rod or burn out your starter motor

Before you attempt the compression test after the diesel soak, spin the engine over for 10-15 seconds to clear the cylinders of any excess diesel.

You will need to change the engine oil very soon after the engine has been first run (no more than 15 mins light running or if it sounds reasonably healthy, almost immediately) as the diesel will have contaminated the oil (listen to me - ever the optimist)

If the previous owner was telling the truth about engine condition, you should hear the joyous burble of 8 pots soon enough

Russ

[mad cyclist]

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spinning it without the plugs will do no harm in my opinion , i did the diesel trick on an engine i was stripping down it worked well.

rgds Nick

[Arbman Al]

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Inlet manifold is now off - not a pretty site:-

Heads off now??

[Arbman Al]

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And another one:-

[GDPR]

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mmmmmm......

seen better Al:shock:

Do not pass Go, do not collect £200, start seeing if your head studs will move.......

Sorry fella but that be a mess........... almost a reason for draining down the coolant if laying up for a while.........

Russ

[Arbman Al]

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kryten wrote:

mmmmmm......

seen better Al:shock:

Do not pass Go, do not collect £200, start seeing if your head studs will move.......

Sorry fella but that be a mess........... almost a reason for draining down the coolant if laying up for a while.........

Russ

Had a feeling you were going to say that

Any tips on removing the head studs - gentle heat from a blow torch maybe?

Al

[GDPR]

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You like fires?

Good soaking in penetrating oil after removing the nuts - if you have the special tool give it a go - there is plenty of info on removing heads on this forum that would be easy to find with a quick search - I suggest you have a look and get stuck in!

You might find they come straight out........ all the very best of luck Al.... it's the job we all fear and no 2 cars are ever the same with this....

Russ

[NickA]

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Is that my imagination but in the pic it looks like the inletmanifold bolts have sheared in the head?

I've always used triple lock nuts on the studs after soaking overnight with penetrating fluid,but if they're going to shear then hopefully it's at the block end otherwise it's the rope trick.

Personally give the state of the heads, I'd have the engine outso you can do a complete clean and assess. At the very least I'd want the core plugs out so I could flush as much of the muck out of the waterways as possible.