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sandandlime

Engine removal

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Hi chaps,

 

Went down south for a post winter run a few weeks ago. En route, and after about 50 miles, an unpleasant knocking sound became very noticeable. Okay, so pulled over and stuck my head under the bonnet to see what it could be but couldn't identify the issue there and then. Strangely coincident was the fact that less than 10 miles before I'd smacked fairly hard into a rubber speed bump - Ludo's exhaust is very low and I should have crossed it square rather than two wheels on two wheels off. Because of this my first thoughts was that the issue must be related to the bump but given that the sound was very evident with the engine running but not moving I can't see what it could have been. Anyway, cutting a long story short, I got back home and put her up in the air for investigation.

 

That was around four weeks ago now (I still had various bits of over winter work to finish on our Alvis and didn't want I start Ludo until the Alvis was up and running). So had a proper look around underneath Ludo a couple of days ago and can't see anything amiss, just a bit of scraping on the bottom of the exhaust. Started her up again and the knocking was very much still present. Couldn't work out where it was coming from but ruled out timing chain, water pump and alternator. I'm a bit suspicious about cam followers but am just guessing really. One thing that I did notice was that the sound wasn't too bad initially but having stopped the engine and restarted it whilst still hot the knocking was noticeably worse. So, I think that there's little choice but to take the engine out and strip it down to find the source of the problem.

 

Given, that I also have a couple of irritating oil leaks from the overdrive unit which I'd like to deal with is it better to remove the engine with the gearbox/overdrive unit attached or should I go for engine first gearbox second?

 

Any thoughts very welcome - particularly those that solve the knocking noise with the engine in place!

 

TIA,

 

Tony

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Any chance of a video/sound recording of the offending noise Tony? Also it's sort of a consensus, and particularly if you're attending to both, that engine and gearbox out as one is the way to go.

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Any chance of a video/sound recording of the offending noise Tony? Also it's sort of a consensus, and particularly if you're attending to both, that engine and gearbox out as one is the way to go.

Hi Pete,

 

Thanks for the quick reply.

 

I did think of recording the knock but thought that asking for it to be diagnosed was probably clutching at far too many straws. I am more than happy to give it a go though. It won't be until later this afternoon though as I got to take my lad into town and run a couple of errands.

 

My concern about having the gearbox attached was the overall length of the thing but at least I suppose that it will hang at the right angle on the hoist.

 

Thanks again,

 

Tony

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Did you eliminate the water pump and alternator by removing the fan belt and restarting for a short while only?

Water pumps can be rather noisy if the pulley rocks on the shaft, but the securing nut is tight.

 

I condemned a TR engine once for this death rattle knock, and was pleased it was only a shagged out water pump pulley and shaft.

 

Cheers

Peter W

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I have had a bad rattle on my 4 cylinder, it was the pulley extension - tighten the long bolt.

 

The other time was a piston with the crown cracking off.

 

Good luck.

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Reference Ash's broken crank experience, you can sometimes diagnose it by placing foot on clutch with engine running and watch the oil pressure. If the crank has snapped the oil pressure is normally lower than normal (you hadn't mentioned it so I suspect not) but depressing the clutch squeezes up the broken edge of the crank and will improve the pressure.

 

Also no dents in the bottom of the sump ? after some off race track action once had a stomach churning knock from the bottom of the engine which was a con rod tapping the inside of the sump ! (TR7 V8). Sorted by welding a nut to the sump and pulling it back out against the subframe.

 

Other suggestions here are good also and worthy of inspection, failing that drop the sump and inspect from inside.

 

Mick Richards

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Mine was a broken crank.

Gee! Thanks Ash. I've got that warm fuzzy feeling all over now!

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As Pete suggested I've made a short video of the engine running and the knocking is quite clear (she also sounds a bit tappety but that's just because the rocker cover is just loosely placed to reduce oil splash). The video is a bit wobbly but it's the sound that's important.

 

The offending sound is here

 

Any guesses?

 

I had already removed the fan belt to isolate the water pump and alternator but hadn't considered the pulley so will go and have a look at that one.

 

Yes Mick, there is a dent in the sump but I don't think that it's deep enough to cause the problem (I think that it has been there for some time). With the fan belt removed I was not inclined to run her up to temperature and restart to see if the note changes again but I did feel that the knock lessened when the throttle was blipped. I don't believe that there is any noticeable oil pressure drop, although it was difficult to be sure on my very gentle return journey when I nursed her the 80 miles back home at 40 to 45 mph. Now, From cold in the garage the pressure is over 80 at 1200 to 1500 rpm.

 

If there's anyway the knock can be addressed without too much work I'd be a very happy man. I've already spent quite a while sorting out various irritations and Ludo is now not too popular with my wife!

 

Thanks again,

 

Tony

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Just like Mine sounded then the noise got Horrendous,stripping mine Sunday and will let ye know.

Edited by TR NIALL

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Have you tried listening to the tappers with a piece of tube 1/2 ins plastic or copper with the rocker cover off, are all the rocker clearances still about right , if its a damaged valve or seat I would expect a loose tappet. Also check you don't have a bent pushrod.

Edited by potts4a

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Hi Tony,

back in the 70's my then 4A made a wondeful knocking sound. It came from the worn keyway on the lower crank pulley.

Have a look at the easy bits before lump removal.

 

Engine and gearbox out together if necessary.

 

Roger

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Thanks to all for the feedback and suggestions.

 

One of the rocker clearances was a tad on the large size, especially considering that they had been set in within the last 150 miles. So it may indicate a problem.

 

I think that what I'll do is to start by taking the head off to inspect the valves and pushrods and take it fom there. I have also considered just dropping the sump and disconnecting the con-rods from underneath but am not too sure about being able to get everything back properly from underneath - it all feels a lot easier with the block mounted on a stand.

 

First of all though I have to face up to the task of tidying and cleaning my workbench.

 

I'll report back how I get on.

 

Thanks again,

 

Tony

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Tony

 

Roger has made a good point about the front pulley coming loose, so I'd try that first.

 

I had a dreadful noise on my Bentley a few years ago, it frightened me to death because everything is so expensive, but I was starting to get the engine out when a friend told me to remove the fan belt and run it. I did and it was silent, sounded lovely. Bloody fan belt had a flap on the back, it was starting to break up. I saved about £9,990 that day!

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Tony

Roger has made a good point about the front pulley coming loose, so I'd try that first./quote]

 

Unfortunately, I have already removed the fan belt without making anything quieter but yes I'll have a look at things that are more readily accessible before getting the engine out.

 

I really don't want to go there as I'm already struggling to find time to to finish jobs already in progress. Had to change a headlamp unit on our C4 daily drive yesterday after the bulb came loose and melted the holder. Only required removing most of the front end. Couldn't believe that the headlamp actually provides support to the front wing! No wonder I prefer classics!

 

Tony

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Just generally poking around this afternoon looking at all the easy fixes. I haven't found anything. Bonnet and grill off for better access and coolant draining as I write.

 

One thing that I have seen though is that there is a fair amount of oil draining down around the engine/ gearbox joint. It's coming from somewhere higher up but exactly where I can't see yet. This leak was not there beforehand so may be significant. We'll see.

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Did you do a compression check yet?

 

Cheers

Peter W

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Did you do a compression check yet?

 

Cheers

Peter W

That was one of the first things we did. Plugs out and spun-up on the starter. More variable than I would like with 2 & 3 at 185 psi 1 & 4 at 165. Not sure why but the battery wasn't happy by the time we'd finished.

 

My earlier comment about the oil leak was just me being a t**t. It was splash over from the back of the rocker box where it had been running without a cover or with it just loosely in place.

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Compression does not point to an obvious piston or ring failure.

I broke a ring and the cr was 75 psi lower on one cylinder and there was smoke from the breather tube.

Thanks for the video and sound.

Cheers

Peter W

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Have a look at the exhaust manifold to head gaskets, ... my 4A sounded a bit like that when it sprang a leak, thought it was a valve or cam follower gone, very relieved to find the hole in the gasket as I began to take it to bits.

cheers Rob

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Have a look at the exhaust manifold to head gaskets, ... my 4A sounded a bit like that when it sprang a leak, thought it was a valve or cam follower gone, very relieved to find the hole in the gasket as I began to take it to bits.

cheers Rob

Thanks for the tip Rob. I got the head off this evening but haven't looked at anything beyond the immediately obvious yet.

 

I'm off to a local classic car meet tomorrow morning but shoud be able to find a bit of time in the afternoon to probe a bit further.

 

bfn,

 

Tony

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I'm absolutely no expert at this but the noise reminds me of a big-end bearing failure I once had on an MGB; oil pressure was noticeably lower. I could also feel the slight knocking transmitted through the gear lever shaft, but I'm not sure whether that is just peculiar to a crank-related problem. Does sound like the engine should be stripped to investigate though. Good luck, Frank

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