Asking a question and embarrased

[Ian B Walker]

Just fitted a cylinder head to a 124 230TE and the engine is dog rough. To make matters worse the silencer glows red hot, worrying isnt it? It also spits back through the inlet manifold when the throttle is tweeked. Valve timing is spot on, new plugs, leads and distributor cap fitted. Can someone please confirm my worst fears that an inlet valve has stuck open. No had a chance to investigate the problem fully as it happened just before I finished work. A Compression check was conducted last night showing 10, 10, 9, 10 bar. It has been suggested that the mixture may be way out (quite possible) and also that the injection distribution head may be duff (also quite possible). I am open to any ideas. Thank you in advance for your input.

 

[Uncle Benz]

Doesn't sound like a sticking valve to me. More likely a fuelling issue. Not aware of any differences in heads on these per se, but you could possibly have a very high compression ratio if a head with significantly smaller chamber volume had been fitted. Presume ignition timing is correct??

 

[Ian B Walker]

Thanks, yes the iggy timing is spot on (hard to screw that up being electronic) The head is a like for like from the original (same part numbers) Fueling, Mmmmm food for further thought.

 

[C240yaz]

Inlet valve stuck open, highly unlikely. Only thing that would cause this to happen would be a broken spring or bent valve, and that could only be bent by hitting piston, so you can rule that out. it;s got to be either fuel or ignition timing.

 

[Ellsy Tanners]

This might sound crazy and make me look stupid.........but, are you 100% sure the vale timing is correct?
Is one cam 180 degrees out, or is the inlet cam swapped with the exhaust cam?

I once sore a 107 sl 500 with the cam on one bank 180 degrees out, engine still ran but gave wired running probs like this.

Is it a 111 engine or 103? i am assuming its a 111.
Double check the cams positions

 

[beemerjay]

I had a similar problem with a renault safrane my bro in law got the head skimmed and couldn't get compression the cam lock slots were 180 out of sync i.e. thick to the top on the exh and thin to top on inlet and he had them thick on top for both so compression was crap

Check your cam timing right back to first principles remember if the cam is above the rocker arm you want number 1 inlet to have just closed BTDC and the exhaust to be ready to open it changes when the rocker bar is above the cam So be careful, But the same principle applies valve just closed then TDC then the exh opening

 

[MIW615]

To make matters worse the silencer glows red hot, worrying isnt it? It also spits back through the inlet manifold when the throttle is tweeked.

I'm no expert on Mercedes, but from the description I agree with comments above - got to be valve timing

 

[BHM]

Blocked exhaust?

 

[MIW615]

Just fitted a cylinder head to a 124 230TE and the engine is dog rough. To make matters worse the silencer glows red hot, worrying isnt it? It also spits back through the inlet manifold when the throttle is tweeked. Valve timing is spot on, new plugs, leads and distributor cap fitted. Can someone please confirm my worst fears that an inlet valve has stuck open. No had a chance to investigate the problem fully as it happened just before I finished work. A Compression check was conducted last night showing 10, 10, 9, 10 bar. It has been suggested that the mixture may be way out (quite possible) and also that the injection distribution head may be duff (also quite possible). I am open to any ideas. Thank you in advance for your input.

Just a thought, why was the head replaced - was the exhaust silencer glowing red hot before the new head was fitted?

 

[MotardMan]

Red hot zorst indicates a lean mixture...........

 

[dava]

Sounds like the valve timing is out, for the exhaust to glow suggests it igniting late, retarded. Check the valve timing again, if it was 180 out it would not start

 

[television]

A retarded engine will spit back and make the cylinder head very hot to the point of pre ignition.

 

[Ian B Walker]

This might sound crazy and make me look stupid.........but, are you 100% sure the vale timing is correct?
Is one cam 180 degrees out, or is the inlet cam swapped with the exhaust cam?

I once sore a 107 sl 500 with the cam on one bank 180 degrees out, engine still ran but gave wired running probs like this.

Is it a 111 engine or 103? i am assuming its a 111.
Double check the cams positions

Its a 103 engine, single cam.

Just a thought, why was the head replaced - was the exhaust silencer glowing red hot before the new head was fitted?

Head replaced because an exhaust valve had burnt out, taking part of the seat with it. No it was not glowing before.

Checked the valve timing and IT IS 100% correct. Going to change the fuel distribution head tomorrow (couldn't do it today due to successful head gasket change on a 230K and a suspension repair on a 560SEC )

 

[MotardMan]

Ian, you have been busy! I hope you get it fixed, and enjoy a drink at the end of this? Are there any good SEC's out there then? I want one, but am too scared to take the plunge..... ;o)

 

[Legoman]

have you diagnosed the original cause of the exhaust valve burning out , if the fault is on that cylinder and hasnt been rectified you might end up with the same damage.

 

[Ian B Walker]

Ian, you have been busy! I hope you get it fixed, and enjoy a drink at the end of this? Are there any good SEC's out there then? I want one, but am too scared to take the plunge..... ;o)

Yes there are good SEC's out there if you are prepared to look long and hard. I have2 at the moment and they are magic.

Problem solved. Oh so simple. My apperntise had put the plug leads on the wrong way. instead of 1,3,4,2, they were 1, 2,4,3. Makes a wonderful change. Questioning him after the event he had gone by the diagram but had gone anticlockwise instead of clockwise. Thank you everyone for your input. Most valued.

 

[MotardMan]

Make him stand in the corner, and buy you cakes all day, and make the tea. For a week. ;o)

Good result, it is odd, but the simplest answer is always the last one we think of. That is why if I have an issue like yours, I always get a mate to check the basics for me. You'll be having a pint tonight then? Shame, cos I thought you might be posting pics of the 190.......

;o)

 

[television]

Pleased it all sorted Ian

 

[C240yaz]

I'm surprised it actually ran at all, with only 2 cylinders sparking at the correct time.