1986 1.6VdP general running queries/problems

[Katana550]

Hello all,
Having previously put H892 TWF (1.3LX) into a ditch :mad: - yes it does hurt!!!

I now have C675 TPG; a 1986 1.6 Vanden Plas; However I have some queries regarding general running.

Initially I was getting about 300 miles from a tank full of LRP. I then started to have some strange fuel supply problems that we tracked to a dying fuel pump; this was replaced and all was well again.

A couple of weeks later I blasted from London to Cambridge (M1 - M25 - M11) at about 90-100 mph. Ever since then I am only getting about 200 miles from a tank :banghead:

The car is primarily used only on fast A roads and motorways (usually at 70-80 mph) with very limited town driving.

Occasionally there seems to be some hesitancy from the engine at steady cruising speeds - almost a juddering/hesitancy feeling! Idle is set at about 750rpm and seems rather unstable as well.

There appears to be no leakage from any fuel lines and the car is regularily serviced (necessary due to the mileage I'm doing at the moment - 11,000 in four months!!)

Does anyone have any ideas and/or suggestions?

Also, does anyone know someone near Cambridge or West London (Hanwell) who is an 'expert' on Maestros?

Sorry for the waffle but the car is excellent and I would like to get the niggling problems sorted!!

Tim

[Dave]

Is the Carb dash pot topped up?
Mine (1300 though) suffers similar problems if the dashpot level gets too low. Fill with clean engine oil - and fuel economy improves, and throttle response aswell.

OR

Damaged / dis-connected vacuum hose. If one of the vacuum hoses has come unstuck you would suffer these symptoms too.

Dave

[Katana550]

Yep, I check the carb regularily and top up the oil - to the top of the damper rod hole only - not the top of the carb (I think this is correct!).

Assuming the Vacuum hoses are the little hoses from the carb to the ECU then they all look fine - but I will check now.

[Katana550]

OK, I checked the carb oil and it was a little low, not for the first time!! Where does the oil go and how often (miles) does it usually need topping-up?

All the vacuum hoses appear fine and connected - no kinks or holes that I could see!!

Anothere question :( - the engine leaks oil (they all do this sir!!) is there any simple way to solve this or do I need to remove the head and get the sufaces machined perfect?

thanks

Tim

[e692wtt]

Sorry to be the bearer of bad news, but I think a high speed blast for a couple of hours has caused damage to the exhaust valve seats in the head. We can get away with fast thrashes using Unleaded fuel with a 'Lead Replacement Additive' (I use a Millers product in a clear plastic bottle with a green cap at a fiver a bottle - can't remember its name...), and the S-series 1600 will run better on Shell Optimax or one of the other 'super plus unleaded' fuels that are coming out again with the Fuel Additive added to it as per instructions.

Early publicity from Esso for its own Lead Replacement Petrol advised that if one expected to drive fast on the motorway, or use the car for towing, and the car was designed for Four Star and not Unleaded, then converting the cylinder head (hardened valve seats) was the way to go. I have only used the stuff once, during the 2000 Fuel Crisis when there was nowt else.

If your car is like my Monty 1.6 (same engine, Leaded only) I would expect it to use less fuel over the next days as the engine will run more efficiently after a good thrash (blows the muck out, etc). It's not like the weather has been cold and the car has needed more Choke for the cold mornings (mine gives 27mpg in the winter and 31mpg during the summer).

Check everything mentioned above (vacuum hoses, ignition electrical connections etc) and hope I'm wrong and you are lucky. There are people on this Forum who are using Shell Optimax on its own and seem to get away with it for now...

The other other Rich.

[Dave]

Mine gets topped up about every 1000miles. I guess it leaks through and gets burnt with the fuel. I fill up to the first collar. (bottom of the threaded part)

Check all of the right angle joints in the vac hose - bend them around a bit to make sure they arent secretly split!
Try removing the end of the one that goes to the vac advance on the distributor - give it a suck (sorry - may not taste great!) - you should feel resistance. If there is no resistance perhaps the vacuum advance diaphram in the distributor is split.

Dave

[Wonko_The_Sane]

I get about 250 miles to a tank on my 1.6 auto..thats unleaded. Gets thrashed a lot too..;)

If your 1.6 is an S series, then you won't find the vac advance on the distributor..it's on the ECU. Same test applies though.

Like you, and I suspect most maestro owners out there, I'd LOVE to know where the dashpot oil goes..I carry a capped syringe in the glovebox full of oil for topups.

Mind you...I tend to use ATF in mine...

[MGTurbo]

Dashpot oils... A fine art in itself. My car prefers ATF although my AFR gauge shows it needs a heavier oil on initial depression of the accelerator pedal.

If you've noticed a drop in fuel economy and a misfire when wanting to accelerate then you could have burnt the valves out. The S series seems worse for this than the A series. A compression test will reveal all.

Gareth

[MaestroMatt]

Is there a hard and fast rule about how long you can use unleaded before the old valve-seats will burn out? I don't drive particularly fast (too mean to pay for the fuel!) but am driving a mechanically unconverted R Series car on Optimax (with only the timing changed). Should I be using an additive to protect the valves until I can afford to have them done or do I have a couple of years of motoring before I start to get misfires and bad-running?

[MGTurbo]

If you never drive above 3000rpm your valves and seats could last 10-20k depending on how much lead memory they have. I managed to burn out the valves in a couple of thousand in my auto VP but thats because i liked to cruise at 70-75mph which is quite high revs on a 3-speed auto. They only long term solution is an unleaded head, but even then the valves can still burn out first, then put higher spec valves into that head. Or, get an old head converted. More expensive yes but you'll save money in the long run if you do lots of miles.

Gareth

[E_T_V]

Do a compression test and see if any of the cylinders are low. If so you may have burn a valve out. I once did one in towing a trailer on the motorway and that was a S-series running on LRP, then it went to the big race track in the sky, (aka Scrapyard). If it is a burnt valve then it can be fixed but probably better going for new valveseats and valves which as mentioned can be quite expensive.

On the lighter side it might just be you've got crap in the carb or the float isn't quite seating properly leading to it richening up the mixture. Have you noticed any change in spark plug colour? Grey/Brown is what your aiming at. White and your running too lean, black running too rich. Check them after a good run as the choke always turns them black. You might just have a dodgy plug/lead/coil which is causing paritial misfires leading to you compensating by putting your foot down more to compensate automatically. I'd recommend: Compression test, if nothing bad found, Check all vacuum stuff, Then new plugs, HT leads, new dissy cap.

Hope you get it sorted

Dan

[e692wtt]

I've heard elsewhere that the carb-equipped engines run better with ATF in the dashpot. Certainly my 1.6 Monty runs better with 10w/40 in the dashpot than 20w/50. My dashpot gets checked weekly (with all other regular items) and it quickly uses much of the oil (couple of miles running) but the level then stays put at a level where the dashpot's 'piston damper' is still in the oil and so still works as intended, for months if left alone. I've topped up with ATF tonight and will let you know what effect it has.

Unbelievably, the factory stated that the dashpot oil should be checked/topped up at every service - every 12,000 miles. The Morris Ital was given a carb dashpot with a larger capacity as a contributing factor in that car's "groundbreaking 12,000 mile service intervals - first for a british car". I don't believe it ever worked in either car... Mind you, the Ital was the world's first production car with Asbestos-free brake pads, which WAS "groundbreaking".

The other other Rich.
;)

[matthewsemple]

I have run a 1.3HLE with SU carb, a MG1600 with Twin-Webers and an MG turbo with SU carb/turbo on LRP and have never had any of the trouble mentioned above. I reckon I have driven at least 40,000 miles on LRP in the three cars since its introduction in 2000.

The cars have all been used in all driving conditions including one weekend when I drove 800 miles in the 1.3HLE when I went to stay with relatives in Kent and forgot the tickets to the concert I was going to in London and had to come back to Bristol to get them!

Regular oil changes and other maintenance is much more effective in keeping the engines happy than choice of petrol.

[Katana550]

Hello all,

Well the saga continues!!!

I have shecked the compression and it was an even 12 Bar (175 PSI) across the board so I assume this is OK :rolleyes:

I have also replaced all the vacuum hoses and ansured that everything (and I mean EVERYTHING is tight!!)

So, at this stage I now get about 230 miles from a tankfull - Does this seem acceptable?

Let me know what you think

Thanks

Tim

[H48HPE]

I know my car is a 1.3 but its doing about 270 miles to £22.65 (30.37 litres) thats about 42 mpg i estimate

if you work out how many mpg you are getting and post that it will be easyer for people to compare because not everyone runs their tank to empty

just a suggestion

andy

[matthewsemple]

Originally posted by H48HPE
I know my car is a 1.3 but its doing about 270 miles to £22.65 (30.37 litres) thats about 42 mpg I estimate

if you work out how many mpg you are getting and post that it will be easier for people to compare because not everyone runs their tank to empty

andy

Trip computer in my MG1600 calculated that I was averaging 39.9mpg on a recent trip to Kent.

[MaestroMatt]

The one in my VP tells me I am doing between 33 and 39mpg on average on my daily commute which is reasonably trafficy. It is more like 38mpg on a long journey. For an old petrol car, I would think anything above about 32mpg is acceptable.

[MGTurbo]

230 miles is a bit poor but it does sound to me like the gauge is reading incorrectly (as they all do) and that a proper calculation is needed. When i run my tank to 'empty' on both of my cars, i always have at least 2 gallons left in the tank.

Gareth

[Katana550]

Hello all,

OK then, here are the figures:

40.74 litres = 10.76 Gallons

254 miles / 10.76 gallons = 23.6 mpg:confused: :banghead: :mad: :censored:

Well, either I'm can't do the sums or my car is f:censored: cked

Let me know,

Thanks

Tim

[E_T_V]

Errmr I make it 28mpg but then I can't count to ten..

Still too low though, have you tried tuning it to make it leaner.. what colour are the plugs after a good run out?

Is the choke turning off correctly?

Just my 2p worth

Dan

[H48HPE]

If the compression test is ok, id suspect its a problem with the mixture/choke or the timing. get it to a garager with proper tuning equipment and have them set it up, and watch them doing it cos if you dont they might just do it from experience by listening, and thats not quite good enough if your paying for it tuning.

not sure how they test timing on an s series but they must be able to

also a point to remember is that if you really are thrashing it all the time the economy will be poor.

andy

[Simon]

I'm sure that I got 250 miles to the £20 worth on holiday in my 1.6 Maestro. Mind you, I do drive gently, and my car's mixture is spot on. Also the engine has only done 45,000 miles. My first 1.6 Maestro that I had was the most economical car I've ever owned, although the performance wasn't much good.

[tony]

hey i have a new pesonal best 185 miles on £30 worth
and its running ok:)

[MGTurbo]

I got 380 miles to £24 quids worth of fuel :D

GK

[threelitre]

Hi!

When going to Peterborough I got 320 miles for only slightly more then 50 quid! New record - never been so low, very gently driven... BTW, my Maestro 1.3 would have done the same for slightly less then half the money.

Alexander