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BMW 740i

Dismantling the engine and a whole lot of cleaning


Now the engine is out I'm still waiting for parts, of course I had a pretty good idea what I needed but getting the parts in France fast is like asking a snail to do a 100yard dash in less than a day. I wouldn't be surprised they still use coaches with horses. You know, like the pony-express.

It does however gives me time to clean out the engine bay which is not really a luxury after 316.000 kilometers, somewhat less than 200.000 miles. Grease and debri built up over the years and turned into a thick black muck.

Cleaning time it is, first thing that struck me was the left engine mount. It looked squashed and was all greased up. I did have a problem because of leaking power steering lines just before the engine decided it needed some serious attention. Hydraulic oil must have leaked onto it and by the looks of it, it didn't do the engine mount any good.

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Another part to order, the right side looks fine so I'm keeping that one. Yes, it needs some cleaning up.

Cleaned up the steering rack.

As well as the rest of the engine compartment.

Time to concentrate on the engine, first thing I did was taking the starter motor out. It is bolted to the gearbox and has to come off first.

At the same side of the engine I took the bracket off which held the compressor for the airconditioning.

And here they are, including the dipstick and the dipstick tube.

Under the engine I discovered a large rubber cap with another hole just beside it. Remember the second hole, I'm going to need it later on.

Like I expected it gave access to the bolts that hold the flywheel to the torque converter. Jeey!

Having undone the 4 bolts and the bolts on the outside which hold the gearbox in place the gearbox was detached from the engine in notime.

The black thing you see on the left in the next picture is the heat exchanger which cools the gearbox, not a very efficient system if you ask me though. It has got it's pro's and cons, since the coolant of the engine is running through it it brings the gearbox up to operating temperatures faster. Downside is it doesn't cool as much as needed in heavy duty situations. To name a few, driving in the mountains or pulling a 2.2 ton trailer. Let alone a combination of the two.

Note: Yes, according to the factory the 4.4 liter V8 in an 7-series BMW is good to pull 2.2 tonns or in the United States of America 4890 LBS.

Enough about the gearbox. It looks like there has been (or still is) a leak at the back of the engine onto the flywheel. Another part to order, the gasket. Sigh...

Anyway, I made a crankshaft timing tool. Needed, and no, not at this very moment but I got it and it's ready to use.

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Remember that hole beside the rubber cap? That's exactly where it goes. There is a corresponding hole in the flywheel, line the two up and bolt it on.

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View from the other side.

Well, the mark "OT" is German for TDC (Top Dead Centre). More or less behind that cooling hose is the marking of TDC on the engine. The tool just fixed it in place.

Now that's done I'm going to get the wiring loom off of the engine. I tell you, there are a lot of sensors and the according wiring. Here you see a detail.

Another detail showing vacuum lines and what have you. It's a maze of wires and lines to disconnect.

Eventually I got it all disconnected, the engine looks very clean without all that stuff attached.

There is the wiring loom, I wrapped all connectors in a plastic bag to keep them from corroding.

As you probably noticed I took the fuelrail out as well, including the injectors. To prevent anything getting in the engine I covered the holes of the injectors up with duct-tape.

Now that's out of the way I took the camshaft sensor out after I cleaned this top cover of the engine. As you can see I also took the waterpump off.

After removing the harmonic balancer I was faced with a thick layer of muck. What's becoming a problem is getting the crankshaft bolt loose, it's referred to as being the J(ezus) B(olt) and for a very good reason. No, not because JB is booze which I happen to like. It's virtually impossible to get it loose.

Tech tip from me, if or when you have to get the bugger loose do it while the engine is still in the car! The torque is so gigantic it took me 3 whole days to get it out having the engine out of the car.

Got rid of the muck and being my own optimistic self I screwed an aluminium (Aluminum in the States) bar to the crankshaft pulley to get the JB loose.

The bar torqued by the least bit of pressure so a somewhat more solid solution had to be found. I had a piece of T-bar laying around and drilled some holes in it. Will it stand the force?

Nope. This is how it looked after the first try, mind you, this is not mild steel!

I tried again using this setup. I know my welding is not perfect but it held.

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I also put an extension on my half inch rattle, which was already welded up because of other big bolts  on other cars that needed some convincion. I know I shouldn't do that but I didn't have anything else to get the leverage at the time.

Hence, it broke.....

Had to get something that was bigger, heavier and was up to at least 1000Nm (about 740 Ft/pound), In the past those bolts where fixed putting 420Nm on it, on this one the torque settings are 150Nm + 30 degrees, another 90 degrees and to top it off the last 90 degrees. In my calculations that's about 1100Nm or in the States about 820 Ft/pounds. Yeah, immense ain't it?

All of this wouldn't be necessary if BMW in their infinite wisdom put a left threaded bolt and thread in it. Missed opportunity in my opinion!

Anyway, I still have to get the JB loose. borrowed an 1 inch wrench with an 27mill socket from a good friend and at the same time found some more extensions.  This setup looks like it's gonna do the job, right?

Wrong! The bugger wouldn't move! Despite all advises I got, not to heat up the bolt I thought of it as a last resort. So I got the ol' propane burner out and heated the bold up till it was talking to me, it said "ping". At that point I asked my wife to act as a counterweight ( she's only like a 110 pounds but everything helps) on the engine hoist and I hung on the extensions.... then it snapped loose! I tell you, after 3 days of fiddling around with the JB I really was happy! There was no way around it, it just had to come off, otherwise I wouldn't have been able to change the chain and the guides.

And finally, off it is! Yep, I had to double up on the T-bar by welding another piece just like it to the bottom of it.

As I said it took 3 days but not looking back on matters, I went along to get the valve covers off.

Then I had to get the covers from the front of the engine off, it took a while sorting all different lenghts of bolts out and keep them in the right order. That was clockwise starting at a fixed point.

Because the chain tensioner is in the cap I just took off I put a tie-wrap around the guide and the chain. This has to prevent any misalignment in the mechanical timing of the camshafts at this very moment. Remember the engine is at TDC, turning the cams can make valves hit the pistons.

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Naturaly I took the cover off the other side as well.

This is what I found, the chain guides had totally disintegrated and came out in small pieces. Those pieces where part of the guides once upon a time in the past.

More loose pieces found in the engine.

Loosening up the bottom cover at the front of the engine produced a lot more bolts which all have to be kept in sequence when puttin them back in. Nothing is simple about these engines.

Going back to where all the guides were gone, some pieces were found in the carter pan, or valley pan if you like.

You can clearly see there is no tension on this chain anymore , even though I strapped it up tight.

Hey, there is a piece left on the guide!

On top of that, the black hole in the middle of the next picture is the opening for the EGR valve. I'm suspicious it's not doing very much anymore as it is fully blocked up.

Great idea those EGR things, not! I once read an explanation of how it should work and it went like this: "Imagine you fart, when you breath in half of what you just expelled into the air and then breath it out again, the air you exhail will be cleaner".

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Then, after this magnificent explanation of "how it works" I produced some brackets to fix the 4 camshafts in place in relation to the cranckshaft. Remember that was already fixed in place using my home made "special tool".

So the cams and the crankshaft are fixed at TDC, stay tuned for the next part in this rebuild, being the rebuilding of the vanos system.


Last update : August 24th, 2017