Engine smokes and pops!

[inca]

Hello,

I'm afraid I've come seeking help as a Land Rover owner. I frequent the usual Land Rover forums but no one seems to have much knowledge of the 6 cylinder rover engine, and after meeting the owner of a rather smart Rover P5, and running our two engines side by side it is clear my Rover engined Land Rover series 3 is not quite right.

History of the vehicle: stood for 10 years plus before being recommisioned and put back in the road with new ignition components zenith carb etc. Ran the same when dragged out of the shed as it does now with all new bits fitted.

The engine starts easily and idles nicely. It is quiet pulls ok.

The issues are two as I see it

Firstly it smokes like a goodun on the over run, ie when coming to the end of a descent and reapplying the throttle, it's white smoke or poss pale grey but certainly not black. Smokeless when under load and idling. Getting head skimmed de coked and new valve stem seals as we speak. Hope this will sort it.

Second issue which is probably unrelated ( in my mind anyway) is a rhythmic pop on idle. It's regular and always there, basically it doesn't sound like a six cylinder engine until you Rev it a little, and even then I'm not convinced all is quite right, very noticeable difference in sound to a proper one. This seems to have everyone stumped. I'm going to get a compression tester as first port of call.

Does anyone have any ideas?

Thank you in advance for your thoughts.

[enigmas]

You've answered some of your own queries! Here are a few suggestions.

Do fit new inlet seals to the valve guides (preferably modern hat type seals...this will require some machining to the top of the inlet guide. Have a cyl head shop do this not your local mechanic. Guide to stem clearance should also be checked on exhaust and inlets. This could get expensive on an IOE engine...but if you want it done properly!

Do take a compression reading of all the cyls when the engine is warm.

Do check the ignition leads with a multimeter especially if they're modern carbon core types. Check also if old style copper wire. If the later and fitted with suppressors check these too or better still throw them away. Leads with varying resistances will cause all sorts of issues.

Points or electronic distributor (pertronix clone?) Check these and especially the condensor if using points.

Do check the internal surfaces of the distributor cap. Dirty internals can cause electrical tracking.

Check the centre carbon rod and the small spring retaining it. It may be missing or not contacting the rotor button.

Do check the insulating ceramic on the spark plugs. Hairline cracks can cause an engine to miss under load.

Do check for exhaust leaks especially at the manifold.

Do check for inlet manifold leaks...spray WD40 at manifold joints and look for smoke and/or change in engine speed.

Lean mixtures cause popping on the overrun.... and surging at constant cruise speeds!

Ethanol petrol will eat fuel lines, corrode alloy and mild steel and eat your carburettor components including the needle and seat. So check out the complete fuel system if you've been using this fuel and laid the car up.

NB. Is it fitted with a power brake booster. If so white smoke is probably brake fluid being pulled by vacuum into the engine and expelled as white smoke.

[inca]

Wow! Thank you very much, the engineering shop that's doing the head is making sleeves to take up the wear in the valve guides and fitting new seals, it's ready now so I'm going to refit.

Ref the power brakes, yes, it has a servo, I'll look into this.

I'll check all the things you've mentioned, thanks for the help

[djm16]

White smoke on the over-run is almost certainly brake fluid from the servo. What servo do you have? The infamous Girling IIb?

If the servo is also leaking air then that would explain the irregular popping etc- weak mixture.

You could try temporarily disconnected the servo vacuum hose and plugging it. I cannot advise running it like that on a public road though.

[inca]

I'm not sure of tha make of the servo, it was brand new a month or so ago, I'll make the check you advise, thank you