Fouling Plugs

vanquishspirit · Post by **vanquishspirit** » Sun Feb 15, 2009 6:02 pm

I have done about 2300 miles in my very early Range Rover since fully rebuilding it. The engine had hardly any wear on the bores so was honed and had all new piston rings fitted. It ha all new valves and cam and followers and bearings. Basically it had done only 53,000 miles before I bought it and has been fully rebuilt except for a rebore. It runs really rather well but has a slight misfire at steady throttle. I have set up the ignition and the mixture as well as balancing the carbs. On inspection of the plugs some of them are perfect, but some of them ae not right and have wet looking carbon deposits which is clearly affecting the running. She does "consume" some oil but perhaps a pint every 500 to 750 miles? I had hoped that this may have been a bit of running in and thats why the plugs were a bit carboned up. If I was forced to guess what the plugs are suffering from I would say fule/carbon rather than oi. Apart from a little puff of bluish smoke on start there is nothing coming out of the back at all. Can anyone give me a clue? Have I got the mixtures different on each carb? Dont think so. Has it got plugs that are too cold? any thoughts please

Davo · Post by **Davo** » Mon Feb 16, 2009 12:14 am

Did you bed in the rings? You get the engine up to temperature, then go to a long, straight, and empty stretch of road and in 4th gear floor the accelerator from about 50-60kmh up to about 90kmh, then lift the pedal and let the car slow down without braking. You do this several times and this loads up the rings and makes them bed in to the bores.

It's very important to do this with a rebuilt engine or the bores can glaze.

If the plugs have fuel on them then check the dizzy vacuum advance and all vacuum lines - these often get forgotten and can lead to all sorts of fun.

Let us know how you go.

disco2hse · Post by **disco2hse** » Mon Feb 16, 2009 12:20 am

Tough call. There are many reasons for why you may have fouled plugs.

How bad is bad? Are the plugs really fouled up or just a little blackish?

I am not at all certain why your engine needed rebuilding after so few miles (I assume you are in the states??), but some causes may be:
- hotter plugs required (cheap and easy solution to many problems)
- carbs not properly set up and balanced, although if this were the case you would have other symptoms such as rough running at idle, poor acceleration, etc.
- spark plug leads are leaking spark (new leads, another cheap solution)
- blown head gasket (is there any blow-by coming out of the oil filler tube?)
- valves are not seating correctly (again, is there any blow-by?)
- valve springs are weak (as above)
- timing is out (what is the acceleration and max rev range like?)
- using the wrong fuel (I would think high octane, unleaded, no bio-gas)

Of course if they are just a little blackish, and you have only done a few thousand k's after a big rebuild, it is likely that it still needs bedding in. How long have you run it each time you have been out? You need to run the engine at full running temperature for a decent period of time, I would say a couple of hours minimum. Only after then will you be able to tell if there are any real problems. Was everything properly torqued after bedding in?

What is the temperature range like? Does it get hot, does it stay at the same, more or less, temperature?

Burning .5 litre for every 1000k's is high. That much for 2500 k's is more acceptable. Are you losing water?

vanquishspirit · Post by **vanquishspirit** » Mon Feb 16, 2009 8:03 am

lots of ideas and questions there, let me try to answer some of them.

First the engine needed rebuilding becasue it had stood for 30 years and was seized. It runs beautifully and is smooth and quiet. The plugs that are bad are really quite cruddy, i.e. quite a bit of carbon build up around the electrode.

I have done a compression test and all is well, although I have not done a leak down test which I suspect will be the real answer to what the problem is. I did not do any particular run in program other than to adopt the recommendation in the original RR manual from 1970. which was avoid high revs until after 3000 miles. A lot of the usuage has been shortish hops, e.g about 10 to 15 miles in my local area.

It does not get hot at all. In fact the guage is cold side of the middle and the heater is not very hot. I wondered whether I should change the thermostat.

It was all correctly torques down and there is no pressurisation of the crankcase as far as I can see.

All new valves and springs were fitted.

what do you guys think about fitting a hotter plug? Will it help?

Also wondered whether the coil may not be man enough and whether I should fit a power coil and or electronic ignition?

map1275 · Post by **map1275** » Mon Feb 16, 2009 10:58 am

Handbook running in procedures are intended for an engine that has already been factory tested on a dyno at RPM you don't really want to know about. Essentially most of the hard work was done for the new owner. The rest is settling in.

You now have at best, a reconditioned engine. This requires you to do ALL the work without a dyno. This has already been discussed. However I learnt it as go find a long steep hill to load up the engine. Of course while keeping an eye on the temp gauge and avoiding any extremes.

15 miles is just enough to foul the plugs and tease the thermostat. Doing a fast lap of the London ring road (when its not blocked), or London to Devizes is running the engine in.

Puff on start up is either guides (which you haven't mentioned) or an over fueling issue (needle and seat).

vanquishspirit · Post by **vanquishspirit** » Mon Feb 16, 2009 12:19 pm

this is great colour, thanks. I did take it for a 123 mile run on saturday and to be fair it was running better when I got back. I did not put guides in it as I had not belief that they would be worn, may be a mistake. The very early ultra low compression engine that it has did not have any valve stem seals fitted, so they may always be vunerable to a little smoke. The carbs were sent away and overhauled by a well know company so should be excellent. I will try some hotter plugs and I will also take it for a bit of harder work out. I suspect that I may have been a bit too careful with it and may be glazed the bores..shoot.

vanquishspirit · Post by **vanquishspirit** » Thu Feb 19, 2009 3:08 pm

So I just took the Range Rover to a guy who builds these engines for a living. He reckons that as I am bunring oil on start up this is likely as not valve guides. My engine would have originally had rubber rings on the valve stems which dont do the job. Didn't refit these as I was told they were useless. This guy can machine in a seal to the existing guide and thinks that should save the day. That said he also says there is a slight chance that the bores have been glazed by the modern oil being too thin. In fact I have put in Duckhams classic 20/50 which is supposedly engineered for older engines. He is still cycnical of this oil and reckons all modern oils are too thin and will run past the pistons and may have glazed the bores. He says buy the cheapest oil you can find and run it on that, it will not do it any harm and will not run past the rings like thinner modern oils. What do you all reckon? He is speaking sense? thx for the help

Larosto · Post by **Larosto** » Thu Feb 19, 2009 6:34 pm

Hi,

I run 20W50 in my engine, changing it every 7500 km, and it`s cheap.
I overhauled my engine, new bored and new pistons, but like you, I didn`t renew the valve guides. So the oil consumtion of my car is about 1,5-2 ltr on 1000 km, it depends on journey and driving style. There isn`t blue smoke coming out of the exhaust pipe normaly, but if I go downhill without throttle and then suddenly give throttle, there are blue clouds at the exhaust pipe.
I think and I hope it is not serious.

kind regards and wishing you the best

Horst

map1275 · Post by **map1275** » Thu Feb 19, 2009 9:57 pm

You may want to re read what you have written, as you have said it isn't the valve guides but it is.

Simple answer in the first instance: head off new guides (all the consumables), especially as you have put new valves in! Otherwise you will have to do it again later, which is where you are now.

How is he going to machine this new groove on car?

I understand that the original design of stem seal is ultra simplistic. Hence why you have the choice of fitting the later guide and full stem seal.

If you want to put poor oil in your car then do so. I would strongly suggest this guy isn't going to provide a full written guarantee.

There is a trueism that some modern oils are less compatible with older engines. Different machining tolerances, seal materials...
ie. Mobile One which is a 0-50 (I think) can have some strange effects on your oil pressure at hot idle. Hence why most manufacturers provide a choice.

However, if you are running the grade that the factory recommend and keeping it clean, there should never be a problem.

Personally I like the idea of anti sludge agents. Especially as Rover service intervals are outside what ANY oil manufacturer say their oil is good for.

disco2hse · Post by **disco2hse** » Thu Feb 19, 2009 10:21 pm

Agreed. The advice I have received most often is to use mineral oils and use the grade specified for the engine, as opposed to synthetic. I change every 5000k's, filter at 10000k's.

So what you are saying is that you have no seals around the valve stems? Possibly this is why oil is getting into the cylinder

Also, what's in it for him if you use cruddy oil... He makes a living from rebuilding engines I think you said.

vanquishspirit · Post by **vanquishspirit** » Sat Feb 21, 2009 7:40 am

ah sorry MAP 1275, you have jus run into a British coloqualism. "likely as not means more than likely it is !

Anyway, there are no stems seals on the valves as there weren't any when I stripped it. The old oils were meant to be much more viscous and unlikely to run as easily down the valves guides. Now I have fitted a higher output oilpump there will no doubt be much more oil at the top of the engine in retrospect. Rover V8's are not renowned for massive oil flow at the top, in fact you can quite easily take he rocker covers off a running engine without fear of being splattered. Anyway, all of this tellsm me I better take off the heads and have a look. Hopefully the bores are ok, there is not much oil coming out the back on normal driving so fingers crossed the bores are not glazed. New valve guides and seals seem to be the answer. I will report back when done. thanks for the advice guys.

disco2hse · Post by **disco2hse** » Sat Feb 21, 2009 10:37 am

Hmmm, classic mineral oils are more viscous than many newer synthetic oils only until the oil heats up, then they are thin. Newer oils start off thin and stay at the same viscosity over a much wider range of temperatures, which means your engine is less likely to fry at very high temperatures because the oil is still performaing its job of lubricating and taking the heat away.

The reason you might have problems with synthetic oil is not beause of their viscous properties, newer synthetic brands are much better. The problem is that in some older engines the oils have a tendency to degrade metals such as bronze bushes, etc. They can also have a nasty effect on natural rubber but then mineral oils are not much better.

What your guy said about 'thin' oils is bo***cks.

vanquishspirit · Post by **vanquishspirit** » Sat Feb 21, 2009 4:16 pm

thanks Disco2 HSE. So what will cause the bores to glaze then? Is it modern fuels that leave a residue which then hardens off and renders the piston rings unable to do the job they are meant to? Anyway, I checked my compressions which are all about 120 to 140 pounds. Bear in mind this is the very early RR with a 10.5:1 compression ratio. I am assuming that becasue the comps are all good then I dont have glazing. Time will tell. thx Andrew

disco2hse · Post by **disco2hse** » Sat Feb 21, 2009 8:33 pm

This link may help to explain how your engine is possibly glazed now and how it should have been run in.
http://www.ntnoa.org/enginebreakin.htm

It is entirely possible that your cylinders have been glazed. Whether you choose to do anything about it is up to you. As you said, it is an old engine and eventually you may decide (in a few years) to replace it with a newer model. Spending too much time and money on it now may not be worth the expense. Up to you of course.

vanquishspirit · Post by **vanquishspirit** » Sun Feb 22, 2009 8:06 am

thanks for that which is pretty much what I had ready on the net. I will take the heads off an let you know how I get along. Oh by the way its a fully nut and bolted original 1972 Range Rover hence I want to keep the original engine.