Noisy engine & lack of power at speed

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MorrisJohn
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Noisy engine & lack of power at speed

Postby MorrisJohn » Mon Aug 10, 2020 10:29 am

I wanted to run my car’s engine symptoms past you to see if there’s anything I’m missing here.

Basically the car had developed a misfire (prior to which it was fine) and the electronic ignition was suspect, so it was put back to points and condenser.

Since then it seems to run and sound pretty good up to around 35/40mph. Beyond that is when the problems start.

Under any kind of load (i.e. even a slight uphill gradient) there is just no power beyond 40mph, and if going faster than that it’s an effort just to try and maintain speed. On anything more than a slight gradient it loses speed. It will pick up speed from a low speed going uphill, but not particularly well.

Furthermore. It sounds tappetty over 40mph under acceleration. Trying to go uphill at all over this speed and the engine sounds clatty. Best way I can describe it is like an old clatty diesel engine sound. It sounds pretty healthy to me at idle and when revved, and also pretty healthy and normal at low speeds.

On a flat motorway it’ll struggle to go beyond 50mph. It should be capable of cruising at 65/70mph.

I should add it’s a 1098cc engine mated to a Ford Type 9 ‘box. Both of which were professionally reconditioned and installed during an extensive restoration. They’ve done around 3,000 miles since (all of them until this issue trouble free).

So far...compression test was carried out and all cylinders had consistent and healthy pressure. If I remember correctly it was 20 bar, 190PSI. I’ve also checked no water is getting into the fuel system and all seems good.

The points have been replaced, the condenser has been replaced with a better quality one and the rotor arm has been replaced. The timing was then reset (unfortunately the marking teeth underneath are missing, making it more difficult). Despite trying several different dizzy angles around the Haynes given one the problem persists. It’s definitely a little advanced at the moment as it’s running on sometimes when switched off. It’s currently set to 12 degrees.

So I intend checking the valve clearances under the rocker cover (separate post, thanks for the help with that). I will set them to 12 thou initially and see how it goes (and perhaps then try 15 thou to compare performance and noise).

I’ve also ordered a new dizzy (25D), with the vacuum, from accuspark to eliminate the possibility of sticky advance weights or faulty vacuum. Once that’s on the timing will be done again and fingers crossed it’s solved.

Is there anything else that I could be missing here? If these measures don’t fix it, what next? Carburettor needle?

I’m new to all this and I’m learning as I go, any advice in layman’s terms would be appreciated.

Thanks :D
The Morris Minor, it’s one of the family.

newagetraveller
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Re: Noisy engine & lack of power at speed

Postby newagetraveller » Mon Aug 10, 2020 1:37 pm

Lacks power going up hills and sometimes runs on when the ignition is switched off.

Is the mixture too weak?

Murrayminor
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Re: Noisy engine & lack of power at speed

Postby Murrayminor » Mon Aug 10, 2020 2:11 pm

I would check the timing is correct, tappet under load could be "pinking" or pre ignition

Lack of power, misfires, pinking all point to incorrect timing.
Proud owner of my first Morris Minor

simmitc
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Re: Noisy engine & lack of power at speed

Postby simmitc » Mon Aug 10, 2020 2:26 pm

Check that the air filter isn't clogged and that the jet is returning fully home after pushing in the choke. Re-check compression. If professional restoration, then ask for their advice under warranty. Yes, you want to be able to fix it yourself, but if you do too much then you may invalidate any warranty; and a professional rebuild should last more than 3K miles.

myoldjalopy
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Re: Noisy engine & lack of power at speed

Postby myoldjalopy » Mon Aug 10, 2020 3:08 pm

Could be a number of things. However if, as the OP claims, the timing is too advanced then this would also cause a knocking/pinking noise (bear in mind specific noises are very hard to describe sometimes - clattering, knocking, rattling etc.) Fit the new dizzy when you get it, do the timing and report back.

oliver90owner
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Re: Noisy engine & lack of power at speed

Postby oliver90owner » Mon Aug 10, 2020 4:25 pm

Newagetraveller is likely on the right track. To ‘over-run’ the engine must have a hot spot, or spots, which is providing the ignition when the ignition is off. Late timing or weak mixture is a typical cause.

Some diagnosis is necessary. I would start with checking the colour of each plug after a longish steady run near to the highest speed at which the engine is ‘comfortable’. Hot spots can be plug tips or carbon in the engine.

Another possible alternative could be some really poor fuel.

I suspect the timing - as this seems to have been fiddled with. But that should not actually exhibit itself as a misfire. Electronic ignition modules generally work or don’t - no half-way house - so looking for a poor connection in the ignition circuit would be my starting point on that one (and the resistance of any carbon plug leads would be next).

Carburettor needles don’t suddenly go faulty on their own. More likely a shortage of fuel to the carburettor due to foreign bodies in the system.

MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Mon Aug 10, 2020 9:40 pm

Thank you to everyone for your helpful replies.

To respond to some of the points:

The spark plugs have been checked after a decent run and they look exactly as they should be.

Poor quality petrol can be ruled out as an issue. It’s gone through several tanks from various fuel stations (none of it supermarket fuel) and this includes some super unleaded.

I will double check the air filter.

I will check the jet returns to it’s normal position when the choke is pushed back in.

I’ll get the new dizzy on (hopefully later in the week) and then have the timing re-done. I tend to agree with the comments pointing towards ignition and pinking.

I’ll report back on the progress made. Thanks again.
The Morris Minor, it’s one of the family.

Monty-4
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Re: Noisy engine & lack of power at speed

Postby Monty-4 » Mon Aug 10, 2020 9:56 pm

I've experienced similar symptoms from a few causes (you encounter everything using one as a daily for years):

- Fuel pump points corroded so not delivering enough fuel at higher load/rpm - a lean condition not always detectable from plugs.
- A later HIF38 carb with the economy/cruise vent not blocked off/re-routed - stutter at low throttle at speed.
- Sticky carb piston movement, choke lever, or float resulting in incorrect fuelling under some conditions.
- Incorrect timing.

Good luck!
68' 4-door Saloon, another 'Monty'.

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Re: Noisy engine & lack of power at speed

Postby Declan_Burns » Tue Aug 11, 2020 7:28 am

Check if an test drive to see if the after market fuel filter is installed. If so remove it and see if things improve.
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MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Wed Aug 12, 2020 12:09 pm

Just an update on some further checks I did this morning..

- Removed and replaced air filter (old one looked okay, a little dirt in places, but new one can’t hurt).
- Checked valve clearances under rocker cover and re-set where necessary to .012”.
- Removed aftermarket in-line fuel filter.
- Engine oil checked again (it’s not burning any).

Car started and sounded normal at idle and revving freely when stationary.

Went a 10 mile test run, up to around 55mph. Same issue persists under any kind of load/gradient.

On my return parking it in the garage I could hear a very slight hiss. I checked the radiator and it was piping hot (water level still filled to max). A mechanic pointed out the same thing last week, though it was after a run of 30 miles in 27C heat so I thought that explained it somewhat...but today it’s cooler and the run was short. The hot radiator causes me some concern. Head gasket was checked last week by same mechanic and I was told it was fine.

So...potentially two issues going on.
The Morris Minor, it’s one of the family.

philthehill
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Re: Noisy engine & lack of power at speed

Postby philthehill » Wed Aug 12, 2020 12:25 pm

Have you checked the thermostat for correct action/operation?


MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Wed Aug 12, 2020 12:32 pm

Not yet Phil. Is there any chance you give me a step by step idiots guide as to how to check it?

...and presumably I’ll need to let the engine cool again to do this?
philthehill wrote:
Wed Aug 12, 2020 12:25 pm
Have you checked the thermostat for correct action/operation?
The Morris Minor, it’s one of the family.

Murrayminor
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Re: Noisy engine & lack of power at speed

Postby Murrayminor » Wed Aug 12, 2020 12:33 pm

Has the timing been set correctly, as you stated you had difficulty setting it.
Incorrect timing can cause the engine to run hot.
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MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Wed Aug 12, 2020 12:42 pm

Murrayminor wrote:
Wed Aug 12, 2020 12:33 pm
Has the timing been set correctly, as you stated you had difficulty setting it.
Incorrect timing can cause the engine to run hot.
I don’t think the timing is currently correct so that could be a factor. I’m planning that for Friday, along with new dizzy, but my concern is the place I’m taking it to do that is 30 miles away...and I don’t want to overheat the engine.
The Morris Minor, it’s one of the family.

philthehill
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Re: Noisy engine & lack of power at speed

Postby philthehill » Wed Aug 12, 2020 1:40 pm

To check the thermostat you need to remove it.

Drain the coolant.
Remove the top hose.
Remove the thermostat housing cover. Held by the three nuts. Soak with Plus gas before attempting to loosen.
Remove the thermostat.
Read what opening temp it is set to. Opening temp should be on bottom of thermostat or rim.
Place thermostat in a container of cold water.
Place temp gauge/thermometer in water.
Heat up water and note what temp the thermostat opens at. This should correspond with the figure on the bottom of the thermostat or rim.
If it opens at the set temp refit the thermostat.
Refit thermostat housing with new gasket.
Refit top hose.
Refill radiator.

If the thermostat does not open at the stated temp replace the thermostat.

Whilst you have drained the coolant it may be a good idea to flush the cooling system by removing bottom hose and using a hose pipe flush (via the top of the radiator & block via the thermostat housing) the system with clean water until the system/coolant runs clear.

Good luck.
Phil


MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Wed Aug 12, 2020 2:03 pm

Thanks Phil. I’ll let you know how it’s progressing at the weekend.
The Morris Minor, it’s one of the family.

philthehill
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Re: Noisy engine & lack of power at speed

Postby philthehill » Wed Aug 12, 2020 2:08 pm

Make sure that you have at least a new thermostat gasket before starting to dismantle anything.

These are the thermostat housing gaskets I use:-

https://www.ebay.co.uk/itm/CLASSIC-MINI ... %3A2334524

I do not use the cork gaskets anymore.


oliver90owner
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Re: Noisy engine & lack of power at speed

Postby oliver90owner » Wed Aug 12, 2020 2:46 pm

Question of whether the thermostat is working can be visually checked for flow, with the engine at/above thermostat operating temperature and by feeling the radiator core.

It won’t tell you whether the ‘stat is fully opening or perhaps all information on a possibly blocked radiator core but is a good non-invasive basic diagnosis.

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Re: Noisy engine & lack of power at speed

Postby liammonty » Wed Aug 12, 2020 9:49 pm

oliver90owner wrote:
Wed Aug 12, 2020 2:46 pm
Question of whether the thermostat is working can be visually checked for flow, with the engine at/above thermostat operating temperature and by feeling the radiator core.

It won’t tell you whether the ‘stat is fully opening or perhaps all information on a possibly blocked radiator core but is a good non-invasive basic diagnosis.
Completely agree. beware if you plan on removing the thermostat purely to check its operation, you need to be prepared for a fight as it’s fairly commonplace for the housing to be completely corroded to the 3 steel studs, unless it’s been removed recently or was assembled with copious amounts of copper grease. I would do what tests you can WITHOUT removing it if you aren’t certain it’s at fault.

MorrisJohn
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Re: Noisy engine & lack of power at speed

Postby MorrisJohn » Thu Aug 13, 2020 2:45 pm

Thanks again to all. Progress today, well...if you can call it that...

1. Adjusted valves again to try and improve running. Again to .012”. Made a bit of a mess of it evidently, as on a very short test run it was tappetty at all speeds. Let it go cold, did it again. Some improvement but overall worse than where I started.
I’ll try again tomorrow and hopefully at least get it back to where it was to begin with.

2. Hissing noise after a run I suspect is the rubber rocker cover gasket. While it looks okay it’s stuck on the engine and not on the rocker cover. I cleaned up all the grease and did my best for a nice tight seal for now. A little improvement - but a new cork gasket has been ordered.

3. Radiator - watched the water when started from cold. No bubbles and water initially still (except for car vibrations). After a couple of minutes I could see the water move in a downward direction, presumably when the thermostat opened. Then small amounts of steam beginning to escape - and put the cap back on. The radiator is fully filled and I’m assured with the correct coolant mixture. The top of the radiator either side of the filler cap was very hot to touch, while the actual mesh bit of the radiator was warm and warmth fairly evenly distributed. Heater in the car is also in top notch working order.
The Morris Minor, it’s one of the family.


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