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Discussion Starter #1
Hi guys and girls.
My first post but it's a a bad start I'm afraid. I've just purchased a 318 convertible with the n46 engine, the previous owner had it looked at and was diagnosed with a slipped timing chain. It sounds about right as it sounds like it's got no compression. So what do you guys think is the best route, rebuild or bin the motor and fit a second hand one?
Cheers.
 

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Hope you got it very cheap ... :)

I'd rebuild, depending on how bad the engine and parts are inside, only you can determine this, and how good you are at rebuilding engines. I've done it a number of times so it holds no issue for me, although space nowadays would stop me!.

If you don't want to rebuild it yourself, then choose someone who is known to have done this engine before and is used to it.

If you put a new engine in, make sure it is a good one, at the least, listen to it running first ... or buy it from a reputable dealer who will guarantee it working to standard.

Also talk to a good electrical engineer, unless you get an absolutely identical engine the chances are some wiring will be different, won't match and some modules, electrical systems, won't talk to each other.
 

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Discussion Starter #3
Thanks greasy. Yes it was very cheap luckily.
I'm a marine engineer and build engines for a living so no problem there, I'm just trying to keep the cost down but without cutting corners and ending up back at square one.
Any recommendations for parts?
 

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Sorry, I'm new to BMW, got my first in March and love 'em, wish I'd had one years ago now! I rebuilt Landrover engines amongst others, but I'd take any engine apart without too much worry!

Have a look here, put your VIN in for specific part numbers ... Real OEM

And this place for an online manual ... Manuals

Have fun .. ;)
 

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If you can do it then i would rebuild it.
Done it many times in the past and you know the job is right at the end.
Thake the head off see what the damage is like.
 

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Discussion Starter #7
That's what I was thinking too, no point fitting another engine that might be on the brink of disaster.
 

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Bought a valve timing tool set and the timing was out, so started stripping down and ended up with the head on the bench and surprisingly there are no bent valves. The timing chain and tensioner and guides all look good so haven't found any smoking gun yet. I did notice that the back 2 head bolts had very little torque on them and found a broken plastic fitting running from the water pump to the head so I'm starting to think that its blown a head gasket.
 

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Discussion Starter #11
She's starting to reveal her secrets to me:love:
So I didn't want to get carried away until I've poked around in the bottom, sump off and there's a bit of shit in there but nothing serious, oil pump pick up off and it sounds like a childs rattle 😳
A blast with brake cleaner and loads of old chain guide bits fall out. You can get No 4 big end cap off with the balance shafts in place so off she comes and the bearings kaput.😩
Pump assembly off and the big ends need replacing but the crank is mint so it looks like I've caught it just in time. The good news is that the timing chain and guide must have been replaced recently because it's all there and in good shape.
I pulled no 4 piston and it looks good after a light clean up.
So now it's onto a parts list and weigh up the options.
 

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Discussion Starter #16
Big end bearings arrived and I measured oil clearances and they all look good so cleaned all the remaining pistons and checked ring gaps and again all good numbers so pistons are back in now.
271614
271615
271617
 

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Discussion Starter #18
On to the head. Cleaned the valves up on the lathe and they came up like new.
271619


Nice to see that the stems are wasted.
271620


It's against my religion to refit a totally standard cylinder head so although the port shape is very good there was quite a few steps from machining left over and quite a pronounced step from the head to seat so I've just cleaned things up.
271621


I've skimmed off.3mm to boost the compression which I would rather have done by skimming the block but I'm not building a world touring car I suppose. 😁
 

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Discussion Starter #19
271660


Gaskets arrived so I fitted the new valve stem seals and popped the valves back in. The old seals were rock hard, together with the gummed up rings she must have been guzzling oil.
Anyway she'll soon be ripping the drum off a Dyno somewhere.😁
 
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