Technical Engine knocking sounds after carb cleanup

[tmrsgv]

For your own comfort I would recommend that at some stage you remove and clean that fan cowling. With what you describe you will always be driving with the aroma of stale oil in the car if the heater flap is open.

Part of that 'old car scent' [emoji6]

 

[Vitesse]

Wouldn’t it be easier to take the dynamo off and the air intake hose around the back and then you will have clear access on both sides? The engine can be left in situ, you just need to be a bit flexible to get a socket on the nut at the back in the air intake.

 

[the hobbler]

Peter's suggestion sounds sound---remove the fan belt and then spin the dynamo (which will spin the fan) and hear if there is anything that the fan is catching and bouncing around inside the housing---it could even be a blade off the fan, they are known to come off or get loose.

 

[The Whitakers]

I’d be concerned about the hard spot, when you drop the alternator belt off remove the plugs too and turn the pulley then, there should be no hard spot at all...,if there is you’re in bother....,

 

[plasticpig1972]

I suggest you remove the Cowlings and give it all a good cleaning.
I've just done this on my Giardiniera and the ammount of dirt, grease, bits of old Fan Belts terrible. The Head needed a good cleans between the Fins, filth everywhere.
Alan

 

[tmrsgv]

Will do in the future, I noticed it requires a special tool to clamp it, and that's something I have never tried.
In the meantime I wanted to find that noise source. Got that flexible magnet and endoscope camera but couldn't find anything. Starting to worry that it's inside the engine.

Planning to try starting with the airbox open (as was suggested here). If something is there, it might fly out.
If that doesn't work, I'll probably have to open up the engine

 

[The Whitakers]

Will do in the future, I noticed it requires a special tool to clamp it, and that's something I have never tried.
In the meantime I wanted to find that noise source. Got that flexible magnet and endoscope camera but couldn't find anything. Starting to worry that it's inside the engine.

Planning to try starting with the airbox open (as was suggested here). If something is there, it might fly out.
If that doesn't work, I'll probably have to open up the engine

Mentioned previously, stick your endoscope through a spark plug hole.

 

[plasticpig1972]

Imho it's quicker to remove the Cowlings and give it a good clean.
I've done this on my Giardiniera and it's not difficult and very quick.
Smells a lot better also when engine is hot.
Alan

 

[tmrsgv]

***Update***
Ok. So I took a while because apparently its very hard to find a 13/16" socket....
Removed the spark plugs AND.... Unfortunately found the main suspect. There was a shredded washer and there's piston damaged [emoji20]

It probably slipped inside the valve housing when removing the carb and when tried to start the engine, it slipped inside the cylinder.

Starting damage control... Any useful observations and suggestions what to do from here? (Videos of the cylinder in the links)

(This is my first classic and did only minor repairs and maintenance so I'd appreciate the extra detailed explanations)

Thanks!



https://youtu.be/PLXVYuVB3J4
https://youtu.be/RPKIQlB2Xx0

 

[fiat500]

Starting damage control... Any useful observations and suggestions what to do from here?

That's such a shame and maybe the worst possible source of that noise. It's amazing that you got such good video from inside the cylinder.

There seems to be a lot of damage to the tops of the pistons and to the cylinder-head. I can't work out if you have cylinder-wall and piston-ring damage; that would be an even bigger disaster.

It's possible that if you can be sure to have extracted all of the metal fragments from the cylinders you might get some further use from the engine. But I wouldn't chance it as there may be embedded or chipped pieces of metal which might come loose later.

I would expect to need a replacement cylinder head and new pistons. It might work out most practical and economical to get new pistons complete with barrels. I would, at least, dismantle and tidy the engine components and then consider which parts might be reusable.

So breathe in and make this a winter rebuild. There's plenty of guidance here and elsewhere to help you through.

 

[the hobbler]

Sadly, it is an engine 'heave-out' job. To make working on the engine a lot easiermay I suggest that you buy yourself a cheap engine stand (rotisserie). When bolted to it, you have the ability to turn the engine over and work on it from a selection of angles; saves a lot of humping about. Neat trick--put the part of the engine stand that bolts to the engine on to the engine first, and THEN hump the engine on to the stand.
When you have the engine on the stand, drain the sump and remove the cylinder head---you will probably have to remove the top of the fan housing and the housing by the distributor in order to do this. Prior to taking the distributor out, turn the engine to TDC and mark both the distributor AND the crankcase. This will make it a lot easier to re-align the distributor when you rebuild the engine and are trying to get the timing correct.
Strip the engine prior to ordering anything---you might find that although one of the pistons is knackered, you can get away with a pair of new pistons and a rebore up to the next size OR, if you have a standard 500, there is a 540cc kit of barrels and pistons that are a straight swap for the standard barrels---no machining needed.

 

[Toshi 975]

***Update***
Ok. So I took a while because apparently its very hard to find a 13/16" socket....
Removed the spark plugs AND.... Unfortunately found the main suspect. There was a shredded washer and there's piston damaged [emoji20]
Starting damage control... Any useful observations and suggestions what to do from here? (Videos of the cylinder in the links)
]

OK I am going to suggest an alternative course of action that will have some of the guys on here choking and spitting out their cornflakes and in the long run may just be postponing the inevitable.
If by 13/16” socket you mean the one that fits the spark plugs you just needed a standard 14mm plug spanner socket which is easy to get.
So the damage is already done and unless the piston rings are damaged or there is more loose metal in the bore you can’t make it any worse.
Sadly that looks like the remains of an M6 spring steel Washer which is hardened and have been more resilient than a normal mild steel flat washer. Normal fixing at the carb base should be an M6 nylock not and flat washer. To reassure yourself you could find another spring washer along with the fragments you have and compare the weights. If they match you know you got all the bits out. If you set the piston down low you can look for scoring on the cylinder wall.
Put a little squirt of light oil down the damaged bore, replace everything, cross your fingers and run the engine for a little bit. If it makes any nasty noises or blows out a lot of smoke then you Know that a rebuild is definitely necessary, good luck

 

[plasticpig1972]

Imho you need to strip engine.
Good luck
Alan

 

[Bleeding Knuckles]

***Update***
Ok. So I took a while because apparently its very hard to find a 13/16" socket....
Removed the spark plugs AND.... Unfortunately found the main suspect. There was a shredded washer and there's piston damaged [emoji20]

It probably slipped inside the valve housing when removing the carb and when tried to start the engine, it slipped inside the cylinder.

Starting damage control... Any useful observations and suggestions what to do from here? (Videos of the cylinder in the links)

(This is my first classic and did only minor repairs and maintenance so I'd appreciate the extra detailed explanations)

Thanks!

View attachment 213334

https://youtu.be/PLXVYuVB3J4
https://youtu.be/RPKIQlB2Xx0

Hi, very unlucky. Tom @ the hobbler is correct - get the engine out and as a minimum you must determine the condition of the cylinder bore. Your engine shop should be able to measure everything and recommend if a rebore will work. Otherwise as Tom says a 540cc kit will suit. I would council that you fully strip and clean/flush all of the internal oil galleries and parts, you never can be sure where metal fragments will end up. Lots of help on here - take it slow
Ian.

 

[fiat500]

Put a little squirt of light oil down the damaged bore, replace everything, cross your fingers and run the engine for a little bit. If it makes any nasty noises or blows out a lot of smoke then you Know that a rebuild is definitely necessary, good luck

Definitely worth a try...there's little more to lose. The damage would have to have been even more catastrophic for metal to get into the oil. I wouldn't want to be doing my sort of motoring like that though.

 

[fiat500]

may I suggest that you buy yourself a cheap engine stand (rotisserie). When bolted to it, you have the ability to turn the engine over and work on it from a selection of angles;

tmrsgv is saying he's new to this level of mechanics, so maybe we shouldn't be making obstacles. Of all the car engines in all the world, the Fiat 500 is probably among those making least demand to have an engine stand.

I've rebuilt many engines (Fiat and others) and done so without a stand. In fact, I did most of the rebuild on most recent one on the desk and floor in the spare room/office of the house.

Dave's Toshi 975 suggestion is good and if nonetheless, the engine really is looking bad for the longer term, it could be partially stripped in-situ for an assessment. A compromised, minimal, top-end rebuild might give an engine working no less badly than previously. None of the damage will be visible and the rough internal finish might even help with agitating the fuel/air mixture.

 

[the hobbler]

"Different ships, different cocoa" Peter. I concede that the 500 engine is one of the easiest engines to overhaul on a bench (but Ann would kill me if I tried to do it inside the house!), and I have built-up 500 engines both on the bench (at Radbourne Racing) and on a rotisserie (at home and work). I just think that it is easier on a rotisserie where you can easily turn the engine over to the most convenient working position--just a personal preference. Whichever way TMSRGV decides to go--he must know that we are here to help him.

 

[fiat500]

Whichever way TMSRGV decides to go--he must know that we are here to help him.

We definitely will be...and I hope he gets onto it promptly. That's one of the reasons I want him to be aware that the repairs can be achieved in a fairly low-tech way and with minimal tools and materials input, as long as he's not desperate for perfection and 100% peace of mind.

When I was a lad I was able to fix bicycles and then cars using a very inadequate set of tools and of knowledge. As I've gained experience and money I've been able to treat myself to equipment which has made jobs much easier. Obviously, an engine stand would make life easier, I could also use a lathe and a proper spray booth would be marvelous. But we all have to draw the line somewhere as a consequence of lack of budget, space or simply not having enough need for something as to justify its purchase.

I get away with murder as regards car activity within the house, even though I constantly accuse Sheila of being OCD about cleaning and tidying. I'm very lucky.

 

[The Whitakers]

Varied and viable responses to be taken board there. If it was mine it would be drop the engine out (it only takes 15 minutes ish) ......whilst it’s out clean the fins etc and all that he crud in the fan housing. Drop the head of and have an inspection. After that either rebuild because it’s knackered or hopefully remove anything that’s left in there and if things aren’t to bad de glaze the bores with a little wet and dry and rebuild. These engines in standard form are very basic to work on, if you have a stand do be it great stuff, if you don’t it’s not exactly a massive lump to work with. Strip it sooner rather than later I my eyes. Don’t be worried you have us lot to laugh at you! Sorry I mean support you ......

 

[The Whitakers]

Varied and viable responses to be taken board there. If it was mine it would be drop the engine out (it only takes 15 minutes ish) ......whilst it’s out clean the fins etc and all that he crud in the fan housing. Drop the head of and have an inspection. After that either rebuild because it’s knackered or hopefully remove anything that’s left in there and if things aren’t to bad de glaze the bores with a little wet and dry and rebuild. These engines in standard form are very basic to work on, if you have a stand do be it great stuff, if you don’t it’s not exactly a massive lump to work with. Strip it sooner rather than later I my eyes. Don’t be worried you have us lot to laugh at you! Sorry I mean support you ......

Just to add to this, I am unsure how easy it is to strip the head off whilst the car is in situ? if this is achievable it would be my prefered option potentially before removing the engine.......