996 Hot start issue, Y Cable symptoms?

Hi I’ve just brought my 02 cab out of hibernation. The battery was charged a few days prior to starting by a relative who said it was fully charged in 1/2 hour (It was stored with the cables disconnected). When I attempted to start (first time in 6 months) it struggled the first time then fired up and ran fine for the 20 miles home. Fast forward 2 days, it started straight away this morning, I drove around 10 minutes to the mot centre, waited 10 minutes for the tester to get in the car and it wouldn’t start as though the battery was pretty much dead (I did notice the rear spoiler had popped up ?). He managed to start it with a jump pack, it was running for about 1 hour. I pulled onto the drive and measured 13.6v at idle across the battery terminals. Switched off and on, it wouldn’t start as though the battery couldn’t spin the starter (and again the spoiler went up). When cranking the voltage dropped to around 8v ? I went and fetched a new battery but decided to try the car first and it started straight away twice ? How do I determine if it’s the Y cable, before fitting the new battery ? Many thanks and apologies for the long post.

Hi. This is quite a frequent topic. I bought a y cable, new starter and a battery. Turned out it was the power distribution block (drivers side near gearbox) was green and crusty. I kept the battery as the other was 9 years old. I also replaced and cleaned the engine earth strap and connections To dismantle the power distribution you do have to disconnect battery There is no easy way to check voltages without quite a lot of disassembly which means you can’t then start! I also checked the power pin distribution, close to battery - takes power into passenger section of car (uk) not sure if 996 have these? Mine is a 997 but there are many things the same on this circuit. I’d also check the battery earth connection is clean

I know this is a very common problem, and one that I thought I had managed to get fixed having had a new starter and Y-cable fitted by Friends Green Porsche just before a weekend road-trip to Wales. The car started much more keenly after having those parts changed, whether hot or cold, and didn't put a foot wrong all weekend of a 700 mile road-trip will plenty of stops and keen driving putting plenty of heat through the system. A couple of weeks on the problem has returned and the car struggles to crank even after a short 10 minute drive. I took the Driver's side rear wheel off to check the engine to body ground cable, and whilst there was a bit of surface rust it didn't look too bad. How easy was it to get the bolts undone, as I know most underside fixings on 996s are a pig to get out. Is it worth taking it off and cleaning it up to see if it makes a difference? How to tell if it is different issue such as alternator or this power distribution box? Do you have a part number for this box and how easy is it to change?

Did you cut the heatshrink off where the cable enters the terminal? ((engine end) Mine had many broken cores so I made a new one. https://911uk.com/attachments/1770215857207-jpeg.140434/ https://911uk.com/attachments/img_7447-jpeg.133570/

Quotes source post: 2800826

i was told you can also add a secondary earth strap if you can find a couple of contact points that might be easier to confirm if thats causing the problem

Quotes source post: 2800826

I think the design is similar so access was pretty ok, I did plusgas the body end - but actually it was ok [2004 997] I would also check the Y cable to body connection for cleanliness - its live though so do disconnect the battery. A new earth cable is not that much £30 maybe from memory so its worth doing in my view In your case how old is the battery? it could be an ageing alternator [or component] do you see 14+v when running?

Quotes source post: 2800849

Y cable is new so I would expect that to be ok. Will look at getting a new engine to body earth cable - I haven't removed any of the outer sheath to check it. Just removed the wheel to take a look at the level of rust on the fixing ends before deciding whether to try removing and cleaning at risk of the bolts snapping. Not sure how old the battery is, but I see 14v on the display in normal use. I use the car 4-5 times a week as it is my daily and I don't ever use a trickle charger. Fires up from cold every time without problem, just struggles / doesn't start when hot. Very frustrating problem.

I've had exactly the same - hot start fail and the spoiler goes up! I'm ordering a Y cable and earth cable to do at the same time.

Quotes source post: 2801166

I meant the connection point. Not saying it is the case but a new cable install - you would hope the mating surfaces are cleaned….But stuff gets put back quickly and that step might have been missed. So I would if it were me still check. 15mins once you’ve disconnected battery checked and reset things… (tip put an old folded tea towel on the lower bonnet catch so even if it’s shut by accident it doesn’t catch and make it a much longer job)

Quotes source post: 2801202

How readily accessible is that connection point back to the body? Any images you can share?

This is it. One end goes up front to the battery the other to the jump point on the engine which the Y cable is joined to.

Mine had the hot start issue. Starter was new about 5yrs ago (Hella Chinese one) Y cable looked perfect so I left it. Made my own earth strap as old was fubar The connection above not the best but I cleaned it all really well and applied some protection. I'll let you know asap if what I've done has helped....engine back in and I'll be getting it on the road next week hopefully. The problem is most people replace everything at once , starter , Y cable , battery etc so they never really know which of those was the problem. I'd love to know why this is an engine warm scenario , I just don't get it because you'd think it would start easier when warm and the battery is full wack.

Quotes source post: 2800442

Doesn't sound like a hot start y cable problem to me If it was it would start fine unless it is hot and I mean hot Mine would only refuse to start on a hot day when engine had been running for a while and I tried to start again after stopping for a few minutes On colder days I never saw the problem and I was using mine daily for over 18 months I would pop open the engine lid and give it a couple minutes to cool and then it would start fine So far nothing you have said to me sounds like it's only a hot hot hot problem

my earth was ok and I don’t think it was the issue. The connection point UM posted a pic of looked the same for me and took about 10 mins with some wet and dry and a small wire brush. Dielectric grease for good measure. Instantly better starting hot or cold for me, and I think it was really driving discharges the battery and if the connection is poor then no juice to the front. As I had also been impatient and ordered a battery I put that on too for good measure. If you check it and it’s clean and shiny then that’s good and you know it’s good!

Quotes source post: 2801221

Hi @Uncle Monty - could you give me an idea of where this is in the engine bay (assuming it is engine bay)? Replaced the engine to body ground last night, and that has unfortunately made no difference. Open to any other ideas of where to look for problems