matt-mans 400SE problem - The answer!
Discussion
Finally found the answer of the crap running problem. Talk about sods law, it was actually three problems which kept throwing us off the answer.
To cut a very long story short..... When Matt drove back from LeMans it run as though it was on 6 clys max. The reason was - two of the injectors were stuck shut. We had them cleaned (the report said two were just not working), but having been cleaned/etc they were now 100% fine, so we fitted them - STILL running rough, but a different rough! We then found a diode from the red steering module had burnt out - great! found another fault, replaced it - still running rough! so as a final "lets check everything yet again" - checked the compression of each cly. All showed around 186-190.....except one which now showed ZERO!
OMG! duff valve? piston shot? rings shot? - but zero smoke or noise when it ran??
Took of the rocker cover - all looked fine.... on closer inspection it has double springs on our head (personally never seen doubles) the inner spring has snapped in half, lowering the spring tension and so the valve was never fully shut - hence zero compression.
Head coming off anyway just in case we find yet another fault. So 3 basic faults all at the same time, no wonder we were put off the track a few times.
Anyway, will order new gasket, bolts, springs(inner/outer) collets etc - Rimmers?? Our head has three rows of bolt holes but only two being used? Engine is NCK155, I guess enough info for rimmer to source the parts?
Many thanks to all especially Ed, hope this info might help others in the future!
To cut a very long story short..... When Matt drove back from LeMans it run as though it was on 6 clys max. The reason was - two of the injectors were stuck shut. We had them cleaned (the report said two were just not working), but having been cleaned/etc they were now 100% fine, so we fitted them - STILL running rough, but a different rough! We then found a diode from the red steering module had burnt out - great! found another fault, replaced it - still running rough! so as a final "lets check everything yet again" - checked the compression of each cly. All showed around 186-190.....except one which now showed ZERO!
OMG! duff valve? piston shot? rings shot? - but zero smoke or noise when it ran??
Took of the rocker cover - all looked fine.... on closer inspection it has double springs on our head (personally never seen doubles) the inner spring has snapped in half, lowering the spring tension and so the valve was never fully shut - hence zero compression.
Head coming off anyway just in case we find yet another fault. So 3 basic faults all at the same time, no wonder we were put off the track a few times.
Anyway, will order new gasket, bolts, springs(inner/outer) collets etc - Rimmers?? Our head has three rows of bolt holes but only two being used? Engine is NCK155, I guess enough info for rimmer to source the parts?
Many thanks to all especially Ed, hope this info might help others in the future!
Good news. As 350zwelgje says, I would start with TVR Power, as that is effectively what NCK became when TVR bought them. The springs should really be matched to the cam profile, so it would be useful to know if the cam is standard or has been changed at any time. My 4.3 has double springs - and this was a TVR Power engine.
As for the heads, the later versions only had 10 bolts, as they realised that the outer row was causing the heads to not sit flat. Many people who have the 14 bolt heads (me included) just don't fit the outer row. It is also recommended to fit an ARP head stud kit while you're at it.
7.
As for the heads, the later versions only had 10 bolts, as they realised that the outer row was causing the heads to not sit flat. Many people who have the 14 bolt heads (me included) just don't fit the outer row. It is also recommended to fit an ARP head stud kit while you're at it.
7.
Edited by Number 7 on Saturday 11th September 18:47
AFAIK all NCK engine's had double springs, I know I did on my 400SE,
It maybe worth getting all the springs changed, but there is no need to change the collets etc
You can re-use the head bolts as they are non stretch type. if you do fit new ones, make sure you don't fit stretch type, or as said fit some ARP studs (But they are expensive). Also worth getting the stainless ARP exhaust bolts that ACT do, as they have a smaller head and make fitting a lot easier.
As said by Number 7 I'd either get my parts from V8 Power or JE
Also make sure you get Elring or better head gaskets
You may want to check the camshaft before ordering anything, as if you need a new one then you can get springs to match.
It maybe worth getting all the springs changed, but there is no need to change the collets etc
You can re-use the head bolts as they are non stretch type. if you do fit new ones, make sure you don't fit stretch type, or as said fit some ARP studs (But they are expensive). Also worth getting the stainless ARP exhaust bolts that ACT do, as they have a smaller head and make fitting a lot easier.
As said by Number 7 I'd either get my parts from V8 Power or JE
Also make sure you get Elring or better head gaskets
You may want to check the camshaft before ordering anything, as if you need a new one then you can get springs to match.
Paul/Matt,
you might find when the head comes off that you have a burned valve. I spoke to me dad about this (who has stripped more engines than I've had hot dinners) and he did warn me that the first thing that will happen if a valve stops sealing properly will be ablation of the seat and valve. At best and by a small miracle, you might remove that valve and find the sealing band around the valve and the matching band on the seat are fine, but more that likely the valve will need re-grinding. Worst case is that the valve and seat are FUBAR and you'll need a new seat fitting (machine shop job) and a new valve (valves arent dear for the SD1 engine - dont think the 400SEs have big valves in?).
Sorry to bring potentially bad news, and really glad the car has given up its secrets (they always do in the end!), but its worth making sure everything to do with that valve is absolutely cock-on before reassembly.
Good thing about finding multiple faults when chasing the original one is that the car will probably run/go better than it has for a while.
Good luck, lemme know if I can be of further help.
Ed.
you might find when the head comes off that you have a burned valve. I spoke to me dad about this (who has stripped more engines than I've had hot dinners) and he did warn me that the first thing that will happen if a valve stops sealing properly will be ablation of the seat and valve. At best and by a small miracle, you might remove that valve and find the sealing band around the valve and the matching band on the seat are fine, but more that likely the valve will need re-grinding. Worst case is that the valve and seat are FUBAR and you'll need a new seat fitting (machine shop job) and a new valve (valves arent dear for the SD1 engine - dont think the 400SEs have big valves in?).
Sorry to bring potentially bad news, and really glad the car has given up its secrets (they always do in the end!), but its worth making sure everything to do with that valve is absolutely cock-on before reassembly.
Good thing about finding multiple faults when chasing the original one is that the car will probably run/go better than it has for a while.
Good luck, lemme know if I can be of further help.
Ed.
Edited by ed_crouch on Saturday 11th September 21:49
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