Type 4 or Type 1? Single or dual carb? You could just take the rockers off and see if all the valves sit flat? Tell you if a valve or seat has died? Only time I have seen piston skirt there is when strokers arent clearanced properly. Any chance something dropping down a carb throat?
Took the carbs off this morning before work to get better access, but there's no way I can see anything down the plug holes, no surprise I suppose. Engine was knocking when running. With the plugs in there's still compression but turning the engine with a spanner on the alternator nut it stops turning when the rotor arm points to no 1 and no 3 plug leads. Carbs are 34 ICT and brand new. 1700 type 4 engine. Had a look and can't see anything missing, both carbs look identical inside. Drove 30 miles in the bus no issues last week, but took it out for a spin yesterday and it suddenly started making this knocking noise. All I have done since last week is take the plugs out to check them. No misfiring, felt down on power, but must admit I nursed it home so didn't give it any beans. Was going to buy a magnet on a stick and have a fish around, but think I am probably being a but optimistic! What am I looking for if I whip the valve covers off? Sorry, but my mechanical skills aren't brilliant! Thx.
The thing with type-4 is that if there was "something" lurking next to a plug it would be possible for it to fall or be knocked in without you knowing While you were changing the plugs. But, that would have been obvious just turning it on the starter before it even fired up. If something made it's way through the carb, it could be held up by a valve until it was battered into a shape that could get past the valve but your engine would be running lumpier than usual - would you notice? I would. So, as you say t'was fine then suddenly started knocking it could be something more serious. Babying the van home rather than stopping immediately could be difference between new big end shells and a new crank if a big end let go, it's not the best approach.
Just as a extra check, you could try, taking all the plugs out, manually turning back and forth whilst using a hose to listen, one at a time in each plug hole to hear any difference. Worth a try maybe. The sound of something loose in one cylinder might point one way, scraping only in one might indicate a bigger issue... Overall noise deep down....you get my point. If others with more experience think won't add value, shout as I've only ever used this method to locate other noises, not like this
Instead of a magnet, could you use a length of plastic tubing taped to a vacuum cleaner hose to try and suck any debris out?
It does sound more terminal than a bit of debris, also being Friday tomorrow I don’t think it will be a quick fix, sorry about that alway break at the worst moment, hopefully you can sort alternate transport. All the best.
Didn't notice the oil light on, but I was in such a state not sure I would have noticed anyway! Managed to get a mate to do it in his bus, so at least the prom is sorted.. just got to sort the bus out now. It fired up straight away after changing the plugs, and sounded/ran sweet fir about a mile before it let go. Is there anything I can do to check the valves?
Look at the relative height of the valve stems with the rocker assemblies unbolted.. What may have happened is a valve seat has dropped out far enough to make the engine lock up once it stopped... all the time it was running it kept bouncing back in, and in fact it had probably been running like that for a while. Just one day it dropped and caught.. This is probably going to turn into one of those stories where stopping the instant you heard something and being towed back would have saved some expensive grief later. It doesnt always work like that - when my engine blew up it lost power and made a bit more noise almost like the difference between a concrete and a tarmac road.. While a bent conrod was flailing around in a pile of bits of piston. That engine ran until I decided to stop it, it was still doing about 55 mph downhill..
Managed to get my daughter to the prom in my mate's bus so at least that was a result, although would have preferred to take her in my own bus. So, back to mine.. had a fish around in the cylinders through the spark plug holes with a magnet on a pole thingy, couldn't feel anything. Popped the valve covers off.. all looks normal to me.. nothing loose, slight bit of play in the rockers, I can feel all of the pushrods (valve stems, are they the same thing?) and I can spin them round with the tip of my finger when the rockers are loose. The engine goes tight when the rotor arm points towards the no 1 & no 3 plug leads, but if you give the spanner (put on the alternator nut) a bit of a run-up it does go past the 'lock-up) position, just feels like really high compression- and there isn't really a metallic noise, just like a big compression 'oommph', if that makes sense. When it does tighten up, it does sound like the noise is coming from the back of the engine. Could it be anything to do with the flywheel? Is it worth whipping off the starter motor & taking a look at the flywheel?
Update... now the engine is locked up completely, stupidly tried to free it up by trying to turn it by the cooling fan & managed to snap 2 blades off! Yes, I know. Things are going from bad to worse. Now looking like an engine out & stripdown job. Not really got the knowledge to do the stripdown myself.. can anyone recommend anyone near Solihull that can do this for me.. possibly even remove the engine for me as well?
What do you reckon would be the best/most cost effective way to resolve the problem? Try & get mine rebuilt or just drop a second hand engine in?
You don't know what's wrong with it yet Strip it yourself, honestly. You'll learn something, and if you cock it up...well, it's broken anyway.
I'd suggest taking lots of photos of each part as you remove them and labeling and bagging each one, especially the nuts and bolts.....saves a big headache afterwards. It helped me a lot the first time I took my engine out when it came to reassembly.
I think this may be getting over-egged. Last time I too a head off mine... I did not even remove the engine, I did not strip everything off. I did it in a car park. Exhaust and one heat exchanger off. Jack that side to take wheel off as it gets in the way, then lower onto axle stand. I undid the engine hanger bar bolts and 2 x rear gearbox hanger bolts so I could pivot the engine/box down a bit. I did that to make it easier to shuffle the rear tin out of the way of the shroud tin and better side access to the head bolts. Carb/distributor off to get the shroud tin off. Acc cable off because mine goes through the gearbox hanger - stock does not. Photo below as at this point. Rocker assemblies off, fish out the push rods. Off with his head. * * I might have had to loosen the fan housing to get a piece of tin off between the fan housing and head. Main point here is that you don't have to remove the engine or strip everything off it. The other side of the engine still has the heat exchanger, carb and HT leads fitted and connected, fuel stuff all still fitted and connected, outboard oil cooler still connected, oil left in the engine... If I had indoor space I probably would have dragged the engine out for easier access, but you do what you have to and it wasn't that bad.
Thx Zed.. may have a go at this. If the engine locks up when the rotor arm is pointing to plug leads no 1 & 3, can I tell which side needs to come off, or is it just pot luck? Thx.
