shutting down when warm/hot

[Deleted]

1960 Humber with original straight 6 on twin strombergs.

Can generally starts fine but can so.etimes cut out once after starting and first pulling away. Then it runs fine once its gone beyond cold to warm. After twenty minutes driving it will shut down dead. It will start again on the button immediately, but will go through ten minutes of totally shutting down. Then it eventually seems to get beyond that and stops shutting down, but for how long it would stay okay again I don't know because I always turn back home by then.

Does seem to be getting worse. There are all sorts of possible causes but I wanted to ask people to list whatever possibilities come to mind and I can evaluate any I haven't already thought of. List of additional info to follow.

Any thoughts welcome even if I don't respond to all suggestions made.

[Deleted]

Some additional info:

Stromberg carbs were examined a while ago and reported to be fairly shagged. So could be carbs not functioning properly any more. Have oiled dashpots and shot carb cleaner into air ports and fuel line entries. Carbs are due to be replaced. Could be inlet manifold... When hot, could be leaking air that kills mixture.

Recently fitted new coil and dropped new spark plugs in. Old plugs were very sooty. Haven't checked new ones yet.

Could be faulty coil?

Facet gold-Flo fuel pump looks old, could be failing. It does feel like it's struggling for fuel at times.

Fuel regulator has been adjusted purely by hand/guesswork recently to try and overcome fuel starvation feeling. Seemed to help.

Sometimes the shutdown feels fuel related, but at other times the electrics do seem to be totally dead. I can turn the killswitch (substitute for ignition switch) and get no ignition light/no electrics to start with. I have to turn killswitch off and on again and then magically... I have ignition light and can start fuel pump and star car. So that would suggest a circuit problem somewhere.

Car is still on points but these seem to be okay.

I noticed recently oil had dropped low which surprised me, and also radiator looked low too. This final point makes me wonder if some of this might be related to some seals or gasket failure. There are no obvious leaks underneath, and there is only ever a tiny amount of creme build-up around the neck of the oil filler which I would expect of a 55 year oil car in winter that spends a lot of time sat in traffic.

Its definitely related to engine temp, but could be fuel, electrics, carbs. Worst case scenario might be there's a gasket going which adds to the problem.

Any thoughts gratefully received.

[composimmonite]

Have you checked washer bottle level

My money is on electrics - especially as the kill switch has to be giggled to get it working.
Is the switch a battery isolator type of a key / normal switch ?
Is it fitted instead of the ignition switch which is now disconnected ?
Does the wiring look sound / decent or messy with loads of loose wires and taped connections ?
Could be a previous owner has simply twisted wired together somewhere hidden under tape and they are the cause.
Personally I always double check what a previous owner has done and in most cases rip out any wiring modifications / revert to original / standard.

[colnerov]

Hi, I think you have more than one fault. As composimmonite says check the electrics. The starting up OK then cutting out as you try to pull away sounds like fuel draining back, because it starts on the fuel in the float chamber then has to wait for the pump to fill it back up again. If waiting for the pump to fill before starting helps then that will prove that.

Colin

[Deleted]

Wiring is an absolute riot of mayhem. It's far from being a standard car. I've rinsed the previous owner of all possible knowledge about the car and he wouldn't be able to help with the wiring... it was sold with 'shockingingly bad wiring' listed as a feature.

Kill switches are battery isolator, removable items fitted to track cars. There are two of them... one on the wing and one on the dashboard. I have suspected it could be the wing one in the past as I suspect water gets in there.

I also agree though that this is probably a combination of things and I suspect part of the problem will be carb/inlet manifold based. I'm at a loss about tackling the wiring though. I simply don't understand electrics at all beyond the principles of simple circuitry. It literally is a jungle of taped-together wires. I've tried having stern words with some of the more obvious connectors and taped up joins but I haven't found anything yet that is obviously/noticeably faulty.

Re fuel pump... out of habit I let the pump trundle for a good twenty/thirty seconds before firing up and it can still shut down shortly after starting. I have generally considered the cold start shut-down issue to be a cold weather problem of trying to kick a straight six through very cold, thick engine oil. When I purchased the car at the end of summer it started up first time without problem every time. It's only become a factor in the winter.

[Deleted]

Cheers for these thoughts. It's really helpful.

[nomad]

Electrics - as you're on original points (no electric ignition) you should be able to run a temporary hotwire to bypass all the suspect in-car ignition wiring, then just take the car for a long drive and see if the problem goes away. If it does, you know the car wiring has problems

You now have 2 connections at the coil * a 12 volt feed from the ignition switch * a wire to the distributor.
For testing you still need 2 connections at the coil * a 12 volt "hotwire" feed direct from the battery * a wire to the distributor.
You will need to manually remove the hotwire at the coil to stop the engine as you have bypassed the ignition key.

To check fuel supply,I found it very helpful to add a glass fuel filter just before the carb - if you are getting air in the fuel or no fuel flowing it's easy to see 


Hope it helps.

[colnerov]

Hi, I missed or misunderstood the fact you're using Kill/isolator switches. Are they the Durite type ones? They are notorious in my experience for the contacts furring up when not used for a while. I have had about half a dozen on my Land Rover, I end up having to change them because it's easier than try to clean the contacts.

Colin

P.S. Try taking the fuel pipe off the carb and putting it in a container of some sort, turn the pump on and see what kind of flow rate you get to see if the pump is OK.

[Deleted]

Thanks Nomad and Colnerov,some really useful info. As for the kill switches... Two of these. I can't get to the one on the wing u fortunately. I may need to start taking stuff of tomorrow to check it..



Direct hotwire is a brilliant idea. I'm going to try and rig that up tomorrow if the weather's good.

Cheers!

[composimmonite]

I think you have sort of answered your own question - electrics are a mess. They need sorting asap because if cutting out when warm that could indicate a joint / connection is a problem and last thing you want is it to catch fire.
If fuel pump is electric again it could be electric and not carb / actual pump ! Like coil fuel pump can be hot wired
Get rid of the battery cut outs and have a single cable from battery to solenoid. If you really want a cut out buy a decent item (not two !) or use one like this that attaches to battery -

If you aren't confident with electrics there are lots of book and on line articles to help show you the proper way of doing things.
If wiring is in a really bad mess then it might be worth seeing if somebody is breaking a similar Humber with good wiring and will sell you the harness. Even if you don't swop the whole harness over you can use sections and PROPERLY slice them into your existing main loom to bypass bodge areas.
Basically go back to original spec, get everything working correctly then incorporate additional circuits (fused) for things like stereo, lights, cigar socket, and such.

Good luck.

[andyborris]

Mar 28, 2015 20:48:30 GMT @quatermass said:

Thanks Nomad and Colnerov,some really useful info. As for the kill switches... Two of these. I can't get to the one on the wing u fortunately. I may need to start taking stuff of tomorrow to check it..



Direct hotwire is a brilliant idea. I'm going to try and rig that up tomorrow if the weather's good.

Cheers!

These cut out switches are usually wired to earth and when used cut all the power to everything!

And are pretty unreliable, had new ones not working from the packet!

[Deleted]

Cheers for these thoughts. All useful info.

Quick update... Pulled out kill switches and both seem to be fine with clean, tight connections.

Gave carbs a bit of a clean in situ, topped up dash pots, checked fuel pump. Found a small leak in the fuel line into the pump so replaced hose. Might have been pulling air in.

Drove it a fair amount yesterday and it didn't cut out once. I'm not going to be too hasty about declaring the problem fixed as it will no doubt take me by surprise tomorrow when I drive to the Sussex RR meet, but so far, so good.

[Deleted]

Finally had some time to spend with my car this week while off work. I think the evidence is fairly conclusive that I have either blown a piston ring or the head gasket.

- the breather pipe is whisping white steam. Not plumes of the stuff, but it's constantly whisping. I had never checked the bottle at the end of the breather pipe in the six months I've owned the car but when I did there was an inch of fuel-smelling water and a few gobs of grey oil. Emptied it (into a bottle for reference later on) and drove car a few miles yesterday. There is a small amount of fuel-smelling water in there again this evening.

- Radiator had recently dropped to below the internal structures (ie they were protruding above liquid level) around January time so I topped up with coolant. I haven't paid close attention to when I've topped back up, but at least one time since then, and getting back from the Sussex RR meet revealed the level had dropped once more to below the inner mesh top surface. No external leak.

-Oil level seems to have held but oil seems thinner to me, as though diluted by fuel. Still black and glossy and not leaking anywhere externally, but after a run the oil has clearly been forced up the dipstick holder and when the engine is hot and I wipe and re-check the dipstick there are some prickles/tiny tiny bubbles popping at the top of the oil level.

- there is a small amount of crema on the oil cap. Not much, but then I wiped it off a few weeks back when I checked so this small amount has built up over a few weeks. Also water (or fuel) droplets collected on oil cap and sitting around filler neck.

- small puff of white from exhaust when starting, but not enough to even be noticeable for a nearly 60 year old engine IMHO. Runs without any evident exhaust emissions of any colour. Doesn't smell of anything distinct either.

Annoyingly I've misplaced my plug wrench and the plugs on these old Humbers sit buried deep so I haven't been able to check the new plugs I put in a few weeks back, but I expect tomorrow when I do I'm going to find one or two very 'washed' looking plugs and four or five sooty ones.

Car generally seems to run okay. Starts first time at the moment in this milder weather though it doesn't feel lively for a couple of minutes until warmed up. I suspect I'm running on less than 6 pistons though as the power has dropped a little and the engine seems to buck and shake a lot more than it used to.

I think, if such a thing is possible, I have 'mildly' blown a ring or head gasket. This makes sense with the symptoms I've been experiencing a lot more than an electrics fault would. Electrics would be random, or final. I can almost predict when my car is going to shut down as it is always at a certain point in its warm up period, then it recovers. This would seem to indicate a temperature/performance intersection where something gives, compression is lost, a chamber gets flooded etc, and the engine dies in the momentary loss.

Also, the fact that it currently loses compression above 70mph would indicate its a 'mild breach' that only gives out past a certain operational point.

Will look at plugs tomorrow, and also do a pressure test.

The tragic thing is if I'm right and I've blown something, this will be entirely self inflicted. I overfilled the oil a tad over winter, and decided it would be okay. It was millimeters above the high marker on the dipstick, but I now suspect this may not be the original/correct dipstick. After high-filling the oil, in an insane few seconds of incredibly poor driving shortly afterwards, I over-revved whilst overtaking and flunked a 3rd-4th gear change by a second or two causing a brief second of over-revving that caused a distinct fog of smoke to enter the cabin from the engine bay. Looking back I think the extra oil pressure found a weak point and cracked a ring or pushed on the HG.

Expensive mistake.

[Deleted]

Wellllp, compression seemed very low by my amateur understanding so I took the old girl in and had it tested by the pros. I have uniformly low compression across all six cylinders. Could still be the head gasket, but more likely to be a warped head. Not entirely sure what the future looks like at this point. I was due to have the carbs changed and the whole thing tuned up at the end of May. I may now need to redirect available funds towards a head skim/rebuild if there's enough meat left to skim and the warp isn't too severe, which means I'll have to trundle on with the unreliable Strombergs for even longer. Damn things aren't ever going to get replaced at this rate.

I've been advised not to drive it until it goes in for a strip down, which is fairly gutting. I personally wonder if the cooling system has been shagged out for a long time and it merely appears to not be overheating when in fact it could be approaching total meltdown in traffic jams. Dashboard water temp guage 'appears' to work but never goes higher than a certain point, so could be a temp gauge or display-meter fault hiding the fact I've got krakatoa under the hood. There's never been any tell-tale steam, but if the coolant isn't circulating there wouldn't be, I guess.

I'm being pessimistic here and it might just be that the head needs a very very fine reflatting to make it seal perfectly. Hoping to get the rad and hoses off tomorrow and see what I find regarding the cooling system, and I need to work out if/how I can check whether the water pump is still working without taking it off/apart to inspect it.

[colnerov]

Hi, What were the pressure readings, and what is the compression ratio of your engine? If they are all similar then that not so bad it maybe just general tiredness of the engine. When you have the engine running with rad cap off can you see the water moving in the rad? If so then that indicates the pump is working alright. If it wasn't then it would boil up fairly quickly. Have you tried an infra-red thermometer on it to find out how hot it is getting?

Colin

[nomad]

Not good news - hope you get is sorted as it's an awesome machine!

Would be surprised if a warped head could give uniform low readings across all 6 cylinders (would expect normal on most - 1 maybe 2 low where blown)

I've stripped 3 Hillman engines for my old daily, found all needed a rebore (worn bores - with lip at top) so just put 'em back together and lived with lower power and *lots* of backpressure/fumes in the breathers. Yours might have same issues?

My local garage did a "sniff test" when I thought my headgasket had gone. If you've not had this checked I'd say do it! Is very quick - just remove rad cap - and confirms the headgasket.

Had my last head skimmed & valve seats recut / valves reground - not a 100% fix (still needs rebore/pistons) but it's an improvement.

Unrelated to car stuff - I got an infrared thermometer from maplins last year for under £10 - might help your diagnostics.


Will send some positive vibes your way later today