4200 CC : Problem starting when engine hot

tonycharente

Member
Messages
182
Tony this is great news, I’m so pleased you’ve had success, although it’s early days, so fingers crossed!! I still try to replicate the hot start issue, but I can’t. It hasn’t let me down once since changing the thermostat.
Yes, my fingers are exceedingly crossed ! Thanks again for your encouragement.
 

tonycharente

Member
Messages
182
Whilst I am very much hoping not to end up replacing the crank sensor, two people on the "other" forum have come out strongly saying I will need to do so.
The very thought of having to remove my intake manifold, never previously disturbed, plus potentially getting air leaks at the manifold gaskets, fills me with horror, and that's before I've struggled to get the oil pressure sensor out of the way.
However one of them, a very highly respected specialist, filled me with hope by stating it can be done without moving the intake manifold, but couldn't remember how he'd done it.
"Has anybody with a 4200 or GS managed to change the crank sensor without at least unbolting and moving the intake manifold forwards, please? And just how?".
 

Zep

Moderator
Messages
9,110
I have done several oil pressure senders without taking off the manifold, so I can’t see why you couldn’t do the CPS. It’s tight, and you will need some ingenuity. I used a 24mm spanner, cut down with a socket welded to it for the sender.9647896478

96479
 

philw696

Member
Messages
25,113
My preferred method is to remove the manifold as you can clear the debris from the valley and there will be all sorts in there.
 

TimR

Member
Messages
2,654
Hah....
Ive done this exact job; in fact, I exclaimed some disillusion to @Zep about the pressure sender's removal at the time..! There is so little room I even ground down the crow's foot spanner 'til it was so weak, I broke it on the extremely tight sender's extraction, and had to make another..!:whistle: It was a case of needing to trust that others had been there and done it before, and to just crack on- otherwise I fear I would have turned back for fear of permanently destroying wiring and creating more problems than I hoped to solve...
The intake isnt a tricky removal atall...and it makes the job infinitely easier out of the way !
The sender has wiring ( from the cps) that obstructs access; if it is the first time you have worked on these components, I strongly recommend you make it as easy as possible for yourself Tony...There are wiring harness clips that you will likely prefer to shift too...
Once you know, you know ! But for a first time virgin ( and personally, I have learned that my own wrenching skills are better when I make life as easy as possible) take the easy, slightly longer winded approach, and as Phil says, clean out the birds' nests en route...!
Im not sure why ML advice is insisting that the the CPS is shot. Im not of the opinion that it is a given. I think you cross that bridge when you come to it...:)
 
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TimR

Member
Messages
2,654
As long as it's not a case of "Hickam's dictum" - both my thermostat AND my crank sensor need(ed) changing....
Anyway I'm now waiting to see what happens next...
Ah yes...the constant companion and a personal favourite, albeit in a DJ and dickie bow; I know this truth by a another name. Sod's Law !
 
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tonycharente

Member
Messages
182
Thanks very much for all these latest replies. The more I ponder on the matter, the more I'm thinking that even if physically possible without shifting the intake manifold the more I'm concluding that removing the intake manifold will be the best way, despite all that is entailed. Also, as a consequence, the more I'm hoping that I won't need to, despite the gloomy views expressed on ML.
Unless I do soon get another hot-restart problem it will be some weeks before I really start to feel confident that the new thermostat has solved the problem. Many weeks, even, as I have other, older, sportscars that need to be exercised.
Thanks again to all,
Tony
 

tonycharente

Member
Messages
182
Unless I do soon get another hot-restart problem it will be some weeks before I really start to feel confident that the new thermostat has solved the problem. Many weeks, even, as I have other, older, sportscars that need to be exercised.
Thanks again to all,
Tony
UPDATE
Well, it's now been over three months since I wrote the above... ...and, at the risk of "speaking too soon", I'm delighted to report that changing the thermostat really does seem to have entirely cured my hot start problem. I've just just completed a touristic rally in Alsace (NE France) starting from the Charente (start of SW France) and completed nearly 2500 kms in 8 days with loads and loads of hot starts and did not have the slightest problem restarting. For those that are thinking that my thermostat being slow to open couldn't possibly cause a problem restarting, my thoughts are that whilst in itself that may be true, the slow warm up was throwing up a fault code (P0128, and the ONLY code I was getting) and that perhaps it's the presence of this fault code that upsets the fuel mixture, causing the difficult hot starts I had been (should I really have said that?) suffering from.
I'd removed all the engine bay trim in order to gain better access to replace the thermostat, and I have decided, however, not to tempt fate by reinstalling all the trim until several more months have gone by.
 

tonycharente

Member
Messages
182
FRESH UPDATE
Well, it's now been absolutely ages since Iast posted an update.
I'm delighted to still report that changing the thermostat really does seem to have entirely cured my hot start problem, despite there perhaps being no great logic to it.
For those that are thinking that my thermostat being slow to open couldn't possibly cause a problem restarting, my thoughts are that whilst in itself that may be true, the slow warm up was throwing up a fault code (P0128, and the ONLY code I was getting) and that perhaps it's the presence of this fault code that upsets the fuel mixture, causing the difficult hot starts I had been suffering from. The temperature gauge now goes up higher and a lot quicker and I've not had a P0128 fault code since I changed the thermostat.
I even replaced all the engine bay trim many months ago and even that hasn't caused the problem to return !!!