N47D20 120d no start. Where to?

[Lubed 55]

A competent mechanic should be able to have the rocker cover off and check the cam timing in 2hrs. With the N47 having a track record of chain issues, it would be high on my list of things to check.

[balancerider 702]

@Cammsport - which mechanic is it at currently?

[Cammsport 382]

On 10/8/2022 at 12:28 PM, balancerider said:

@Cammsport - which mechanic is it at currently?

A BMW/MB/JAG independent in Queenstown

[jon dee 500]

On 10/7/2022 at 3:52 PM, Cammsport said:

I asked what was the compression on the other cylinders. "have only checked #1 and #2, #1 is 250psi and #2 is 150". Compression significantly picked up with a bit of oil in the cylinders and then faded again. No air can be heard/felt from the intake/exhaust manifolds.

On this basis I would tend to agree with the mechanics initial advice of "look for another engine". It is impossible to say that there is not some rare and/or bizarre factor (that does not bring up a code) and is stopping your engine from starting. Like gelled fuel for example. But that would be unlikely to cause one cylinder to be 100psi low. And since you previously drove for a long distance without noticing any rough running, I would not be expecting stuck rings, but I guess it is possible.

I sincerely hope that there will turn out to be some rational explanation to this problem, as I hate unsolved mysteries !!! Good luck. 

Cheers...

Edited October 9, 2022 by jon dee

[Cammsport 382]

8 hrs seems like alot of labour, but I'll take it on the chin and move on I guess! Trying to find a motor and I'll start on the swap as soon as I get the car back. 

[Allanw 1051]

So...

135d build coming up???

[Cammsport 382]

4 hours ago, Allanw said:

So...

135d build coming up???

Hahaha, anything on the cards at the moment if I can't source a nice N47D20. I've always been loyal to the M52... 🤔

 

Kidding 👀

[Neil McCauley 248]

23d swap... 🤔

Edited October 19, 2022 by Neil McCauley

[polley 916]

3 hours ago, Cammsport said:

Hahaha, anything on the cards at the moment if I can't source a nice N47D20. I've always been loyal to the M52... 🤔

 

Kidding 👀

I have a complete e39 530d that would make an alright donor.

[Olaf 3236]

8 hours ago, Neil McCauley said:

23d swap... 🤔

this!

[Lubed 55]

I'm struggling to understand how a engine running perfectly at shut down one night, then come the following  morning the piston rings have failed causing major compression loss and the engine not to fire. Is it worth getting a second opinion from a different workshop or doing a little more investigation yourself? It does not seem like the root cause of your problem has been identified.

[Cammsport 382]

7 hours ago, Lubed said:

Is it worth getting a second opinion from a different workshop or doing a little more investigation yourself? It does not seem like the root cause of your problem has been identified.

It seems extremely unlucky to me too. I'm definitely not going to another garage, after receiving thst bill. I would've rather spent that money on a borescope, compression test and leakdown test tools (which I'm now going to do anyway, to double check). Apparently acetone down the cylinders is an old trick to free up seized rings, so that could be a goer too. Don't have much to lose. 

[Lubed 55]

I would hazard a guess that rings don't fail overnight. Sometimes on engine shutdown the crank can spin backwards a few degrees due to a piston not quite reaching tdc on the compressor stroke. The compression then pushes the engine backwards, if the timing chain is worn then the chain jumps a couple of teeth.

[jon dee 500]

This ^^^^^. Happens on older gasoline engines that only have a tensioner on one side of the chain. Engine kicks back on shutdown and the tensioner is now on the wrong side of the chain and ineffective, allowing the chain to get loose and jump teeth. Go to start the engine the next morning and it will not fire due to bad spark timing and/or lack of compression.  

First check would be to make sure the cam chain (or belt) had not broken and the second check would be to make sure all the chain timing marks still lined up. Not sure what the tensioner/guide arrangement is on your diesel engine, or how easy it is to check the cam timing, but as said, that should be one of the basic crank-no start checks. 

The checks that have already been done appear to have covered these points, However, diesel engines are likely more sensitive to a drop in compression than gasoline engines. A friend of mine had an old diesel truck that wouldn't cold start, and every morning we had to tow it at around 50kph to bump start it in a high gear   Once started it would run fine all day. Not going to work with an auto though, even for testing.

Cheers...

Edited October 19, 2022 by jon dee
More info Stephanie....

[Bronsk 3]

@Cammsport

Sorry its taken afew weeks dude had some serious issues with getting injectors out . Figured id fill you in on where im at currently , so seems the intake cam shaft at cyl 4 rear has movement tinyest movement  , the chain timming marks are fine and doesnt appear to have bent any valves but will know more as i go . Not sure if that helps at all. But yea thats kinda where im at currently with the issue on mine. My point being rotate the engine and watch the cam as u turn it . As i recall u saying u had low compression in 1 or two cyl  ,as you may have the same issue

Edited October 30, 2022 by Bronsk

[Bronsk 3]

 been a long afternoon. But have the results of my problem @Cammsport. Chucked up a couple of pictures , wouldnt realy know unless ur removed the head apart from two rockers being ever so slightly lower then the rest

[Bronsk 3]

To check the timing marks in my opinion its definitely a motor out job. As u have to remove sump to even get the back plate off and doing that between the firewall and the gear box would be what nightmeres are made of . once engine out thou its pretty straight forward . only issue we had the the damper plate on the steering being in the way of the drivers side engine mount. Left loom one the engine and disconnected from ecm was alot easyer then trying to unclip the loom etc . Im probably guna be trying to source a new engine as for me its realy not worth getting new valves ,head work ect just working out if its even worth buying new engine or replacing car sadly

[Cammsport 382]

@Bronsk that's a bugger. Some satisfaction I guess in that you found a fault?

Yea I'll pull the motor out regardless and change the timing gear for peace of mind. 

I'm also going to borrow the borescope from work to see if there's any damage to bores etc. 

Edited November 5, 2022 by Cammsport
Horrid grammar

[jon dee 500]

@Bronsk How many kilometres were on the engine before this all happened ?

[Bronsk 3]

4 minutes ago, jon dee said:

@Bronsk How many kilometres were on the engine before this all happened ? .

265000 so its done well to be fear , To be honest im abit perplexed to how exactly it happened though the chain looked fine ,as did the guides my guess is the tensioner has a issue .

 

[Bronsk 3]

22 minutes ago, Cammsport said:

@Bronsk that's a bugger. Some satisfaction I guess in that you found a fault?

Yea I'll pull the motor out regardless and change the timing gear for peace of mind. 

I'm also going to borrow the borescope from work to see if there's any damage to bores etc. 

Yea mite have some luck with the scope ,like the two that where bent where almost unnoticeable by looking at it we had to full it with water to see if they leeked , amazingly the pistons and bores where in perfect condition for the kms was rather surprised, have alook on ebay before you buy chain etc dude u can get full kits with gears, guides, chains etc for half the price ud pay here just watch the shiping prices lol. like i found a valve kit that includes head gasket rockers ect for 500 + 150 shipping . And chain kits ranging from 300 - 600 .

Edited November 5, 2022 by Bronsk

[jon dee 500]

3 hours ago, Bronsk said:

265000 so its done well to be fear , To be honest im abit perplexed to how exactly it happened though the chain looked fine ,as did the guides my guess is the tensioner has a issue .

There is a popular misconception that timing chains last forever and never need replacing. In reality both the chain and the sprockets that it runs on wear. This causes the chain to "stretch" due to accumulated wear, and go slightly out of pitch. Eventually the chain will no longer engage correctly with the sprockets, and the likelihood of the chain jumping teeth on the larger sprocket will increase. The tensioner may also become less effective depending on its design. 

For industrial applications (and automotive applications are no different) a transmission chain is considered worn out once the change in length (stretch) reaches a specified percentage increase over the original length. Putting a new chain onto worn sprockets will cause accelerated wear on the new chain, so it is good practice to change chain and sprockets at the same time whenever possible. 

So yeah... that chain did a good job but I would guess it just wore to the point where a cough or kickback on shutdown caused it to jump a couple of teeth. When you have the chain off, try bending it sideways. if you can form a pretty good arc, that is an indication of a well worn chain !! 

Cheers...

[Spinner99 53]

Just throwing this one out there in case there's a remote chance it may help.  short summary =   diesel crank no start with a dodgy sounding crank, relative compression test showed 1 cylinder needing more power from the starter, problem was a stuck open injector flooding and hydrolocking one cylinder.

 

 

[Cammsport 382]

Mustered up some motivation to get back to the lemon. Found some more lemony goodness. 

Loom, glow plugs, turbo, radiator, intercooler and belly pans removed. Turbo found to have some lateral play on the shaft, so that'll be getting rebuilt/replaced (anyone have any experience with the DIY rebuild kits?). Looks like I caught it early enough and there's no shrapnel anywhere. 

When removing the belly tray, I found the little brass olive that goes in the fuel lines to the injector. Can't find the 2nd one. Royaly p*sses me off that the garage has had such sloppy workmanship. None of the fuel lines blanked. Injector left uncovered. Would be keen to send a sulky email as opposed to bad feedback on Google, but I doubt it'd achieve much. 

Plan from here is to remove the intake manifold and use my new leakdown tester to pinpoint where the air is escaping from. I'll also loan the borescope from work to see if there's any damage to cylinder bores before going any further. 

[Cammsport 382]

Threw the borescope down the injector holes to see what kind of engine I had. All in all, not too bad. Cross hatchings still present and no scoring that I could see. But a heck of a lot of carbon build up on the pistons. See below. Vertical lines on #4 are from fuel seeping down the cylinders when injectors were removed.

And from a top down view, there's an obvious fault on #1 cylinder. The piston is offset to one side which I assume is from the rings.

A lot different to #3 if you were to compare.

A view of the top end shows how bad the carbon build up is.

And a video of #3 so you can see the general condition.

At this point I think I'm wasting my time soaking the cylinders, hoping the rings will free up. I think the engine needs to come out, pistons removed, carbon removed and rings replaced. Will give me the opportunity to replace the timing gear too for piece of mind. If anyone has any tips or pointers, fire away! If the head is carefully removed (all head bolts loosened incrementally), do i still need to have the head skimmed? Was hoping to avoid the extra cost.