N47 timing help! Reward within...

[Cammsport 390]

Hi all, 

I'm after anyone who is familiar with the much loved and reliable N47. A dozen Panhead Superchargers to whoever leads me onto the path that gets this thing going. 

I've just replaced the timing gear on a 2nd hand engine. Followed the procedure in accordance with NewTis. Flywheel pinned and cam looking tool fits beautifully flush on the valve cover deck. Turn the engine over by hand, without plugs or injectors and it's silky smooth. Compression test it and I get 75, 75, 75 and 140psi. Leak down test with 30psi shows 25% and any losses are from the rings (quite good I thought for a motor that has been laid up and cold). What have I done wrong? I'd expect at least 240psi. Throw any suggestions at me and I'll field them to the best of my ability. 

Thank you in advance! 

[Cammsport 390]

Has anyone "bled out" hydraulic lifters before during a rebuild? 

[C-130 Hercules 571]

Do a M20 swap

[Lubed 55]

It pays to double check TDC on No1 cylinder using a screw driver down the injector hole. Are the three lines on the cam sprockets facing each other? Its normal for an engine that's been standing for a long time to have low compression,  compression soon ramps up again after the engine has run for a short period if all engine components are damage free.

[Vass 830]

11 hours ago, Cammsport said:

Has anyone "bled out" hydraulic lifters before during a rebuild? 

Not N47 ones but M54 ones, yes. Not sure if they're the same or similar. Just used vise grips to hold the wee bucket and pull it out of the lifter, then disassemble and clean out. Pretty straightforward. 

[Cammsport 390]

8 hours ago, Vass said:

Not N47 ones but M54 ones, yes. Not sure if they're the same or similar. Just used vise grips to hold the wee bucket and pull it out of the lifter, then disassemble and clean out. Pretty straightforward. 

And do you fill them back up with oil? 

[Cammsport 390]

11 hours ago, Lubed said:

It pays to double check TDC on No1 cylinder using a screw driver down the injector hole. Are the three lines on the cam sprockets facing each other? Its normal for an engine that's been standing for a long time to have low compression,  compression soon ramps up again after the engine has run for a short period if all engine components are damage free.

Have confirmed TDC with a long screwdriver. The 3 lines line up between the cam gears. I am tempted to just put the motor back in and try start it. However if there's a no start condition again, I'll cry 😅. A wee spray of "start ya barstard" near the intake didn't cause a fire either which would indicate it genuinely has low compression. 

[Vass 830]

1 hour ago, Cammsport said:

And do you fill them back up with oil? 

No, I didn't. Not sure if you need to? The guide I followed claimed they would fill right up once you go on a proper drive and the oil pressure builds up. Bit of lifter tick at first is normal. 

[NZE90 9]

Try putting a bit of engine oil into each cylinder, then crank the engine over without the injectors to get rid of the excess oil, then recheck the compression. This method is called a "wet compression test" 

Also how are you cranking the engine over on the stand?

[Cammsport 390]

6 hours ago, NZE90 said:

Try putting a bit of engine oil into each cylinder, then crank the engine over without the injectors to get rid of the excess oil, then recheck the compression. This method is called a "wet compression test" 

Also how are you cranking the engine over on the stand?

Had put about 1Tbsp of oil into each cylinder and it didn't make a difference. This would only make a difference if it was rings. 

Starter bolted up, jumper leads to another car. 

A friendly bloke from the UK forums gave me a call yesterday. He said as long as the leakdown is OK and I'm certain the timing is good, to just put the motor in and give it a go. He had done dozens of N47 timing chain repairs and had never done a compression test out of the vehicle before. Fingers crossed. 

[NZE90 9]

Is it possible there might be some carbon stuck under the valves and preventing them from sealing properly?

[Cammsport 390]

24 minutes ago, NZE90 said:

Is it possible there might be some carbon stuck under the valves and preventing them from sealing properly?

Thanks for your replies. I have lapped the valves and changed the stem seals. They were originally super gummed up. 

I wonder how many engines EGR + CCV have prematurely killed? 

[Cammsport 390]

Engines in. I have fuel (the smoke in the picture is unburnt diesel from the turbo outlet). I have glow. I have crank but i do not have start. Anyone want a rolling body E87 😅

[Allanw 1071]

Well it's got a strong starter motor 😄

It sounds like a couple of cylinders are trying!

Have you thought about trying a tiny puff of easy start?

Do these bleed air out of the injector feed themselves, or do they need help?

[Cammsport 390]

2 hours ago, Allanw said:

Well it's got a strong starter motor 😄

It sounds like a couple of cylinders are trying!

Have you thought about trying a tiny puff of easy start?

Do these bleed air out of the injector feed themselves, or do they need help?

Thanks for your reply @Allanw

Have tried "start ya barstard" and it doesn't sound like it fires any different. 

I've bled them at all 4 injectors until a nice steady stream of diesel comes out. This is also the highest point of the hpf system, so I haven't cracked and bled the system anywhere else (not saying I shouldn't either though I guess). Have also carried out the ISTA bleed procedure via the lpfp. 

[Allanw 1071]

I'm far ( Far, FAR) from an expert... just thinking out loud:

but I'd have thought a bit of starter fluid would mean it would at least make a few more bangs... if the mechanicals were doing their things, at the right times??? Maybe?

The white smoke like that is normally from uncombusted diesel... isn't it? not enough compression to pop it? (I know on a running diesel with a bad misfire, or a leaky injector letting fuel in at the wrong times etc, it can do white/grey smoke).

If you have the injectors unplugged, does the cranking sound even?

Was the motor from a reliable source?

You've had the head off and done the valves, right? No obvious damage then?
Maybe double check the timing process, or better yet - have a new pair of eyes look over it?

Sorry 😬

[Cammsport 390]

@Allanw, you're right, the starter fluid should make it fire if the compression is good. Which makes me think the compression is not good (which it's not, in the original post). But the leakdown test and timing is good. Next to no leaks. 

Which is where I'm lost. Engine was supposedly running before it was pulled. As trustworthy as the next person on Trademe I guess. Have had the injectors unplugged (when I was building fuel and oil pressure) and crank sounded uniform. 

Yip, the white smoke is uncombusted fuel coming from the turbo outlet. It can be seen in the engine bay as the dpf isn't plumbed in. 

Had the valves all apart and they're in perfect condition and dead straight. 

Have had timing checked by two others. 

Where I'm at now is... Drain the fuel tank and put fresh diesel in. Swap out the hydraulic lifters, incase they're not letting the valves get proper lift or duration. 

Thanks again @Allanwfor brainstorming with me. 

[NZE90 9]

I assume the bores looked good when you had the head off otherwise you wouldn't have bothered with the other work? It sounds very close to starting, and i think if you CAN get it started and take it for a decent run it maybe ok. The rings could be stuck after sitting around.

If it were me i would try putting 2 sets of jumper leads on it in the hope of increasing the cranking speed. One set to the battery terminals under the bonnet (like you already have) and another set with the + directly on the starter, and the earth directly on the block.

[NZE90 9]

The other option is putting some product like carb cleaner or upper i take cleaner on top of the pistons and let it soak over night and hopefully break down the carbon. 

You would have to put some oil down the bores after doing this as the solvent will obviously was the oil off the bores which won't help with compression.

I have taken a few N47 engines apart and there was always a lot of carbon around the ring lands. This isn't my pic, but it is an N47 piston with about the same amount of carbon around the ring lands. Thanks EGR!

Edited December 1, 2023 by NZE90