New 924S owner with speedometer, cooling system questions
04-25-2018, 01:46 PM
#1
New 924S owner with speedometer, cooling system questions
Hi all.
Though I have been a member of the Rennlist forum for some time, it has always been for my '73 911T (the air cooled forum).
In the last year, however, I have acquired some water-cooled cars as well: an '88 924S, '86 928S, four (yes four) 944s (2 complete cars, 2 rolling donors, none running yet).
I've had the 924S for about 6-7 months now and am finally getting around to getting it sorted (so my son can drive it this summer).
It has two (2) issues requiring immediate attention:
1. The coolant temperature gauge runs very hot
2. The speedometer needle "bounces" a bunch above about 20mph (and the odometer doesn't work, though the trip meter does).
Regarding the cooling temp gauge reading hot/high, it appears to be functioning because when it was cold here in Austin, it would read at about 60-70% of max, when warm/hot here, it reads about 85-90% of max.
The seller (via BAT -- bring a trailer) told me that it was just a coolant temp sensor ground issue, and I am taking him at his word (after all he gave me a very, very, very good -- dare I say screaming -- deal on a 928S with a bad 2nd gear synchro and non-working AC but otherwise sound car in a two-fer deal).
I am guessing that when it's cold, say below 30 degrees, the normal needle reading would be at 40% of max, not 60%, and 50-60% when the ambient temp is hot, so maybe it really is a calibration/ground issue?
How would one suggest I go about troubleshooting this to determine whether it really is a ground versus something else: bad sensor, thermostat, clogged radiator, etc.? I just got done sorting out all the electrical on an X1/9 I bought (it had priority as I was driving it targa-off during the cooler than usual winter/spring here in central Texas), so am pretty handy with a multimeter and wiring diagram right now (and the Fiat had lots of ground/resistance problems).
The issue with the speedo is more of an irritant. I am guessing that it is the speedo gauge itself and not the speed sensor because there is an issue not only with the speedometer needle not reading accurately/bouncing around -- sometimes it does it continuously, other times it settles down after driving it a while -- but also with the odometer, so my issue is with the whole speedo gauge in the instrument cluster.
Does everyone agree with this or could it be the speed sensor? (presumably, the speed sensor also drive the odometer and trip meter mechanisms as well?)
Can these be repaired or do I need a new cluster? Haven't taken it out yet, but Haynes says the cluster is a one-piece integrated unit.
If so, is the 944 cluster a plug-and-play as I have four of those and long-term will only need two? Or is there someone that fixes these clusters relatively cheaply?
Otherwise, I love the 924 -- I have always wanted one since I was a kid -- and look forward to driving it a bunch once I have these little irritants sorted out, especially since it has great R134 AC while the 911T doesn't and the 928 does but it doesn't work yet (too many projects).
Though I have been a member of the Rennlist forum for some time, it has always been for my '73 911T (the air cooled forum).
In the last year, however, I have acquired some water-cooled cars as well: an '88 924S, '86 928S, four (yes four) 944s (2 complete cars, 2 rolling donors, none running yet).
I've had the 924S for about 6-7 months now and am finally getting around to getting it sorted (so my son can drive it this summer).
It has two (2) issues requiring immediate attention:
1. The coolant temperature gauge runs very hot
2. The speedometer needle "bounces" a bunch above about 20mph (and the odometer doesn't work, though the trip meter does).
Regarding the cooling temp gauge reading hot/high, it appears to be functioning because when it was cold here in Austin, it would read at about 60-70% of max, when warm/hot here, it reads about 85-90% of max.
The seller (via BAT -- bring a trailer) told me that it was just a coolant temp sensor ground issue, and I am taking him at his word (after all he gave me a very, very, very good -- dare I say screaming -- deal on a 928S with a bad 2nd gear synchro and non-working AC but otherwise sound car in a two-fer deal).
I am guessing that when it's cold, say below 30 degrees, the normal needle reading would be at 40% of max, not 60%, and 50-60% when the ambient temp is hot, so maybe it really is a calibration/ground issue?
How would one suggest I go about troubleshooting this to determine whether it really is a ground versus something else: bad sensor, thermostat, clogged radiator, etc.? I just got done sorting out all the electrical on an X1/9 I bought (it had priority as I was driving it targa-off during the cooler than usual winter/spring here in central Texas), so am pretty handy with a multimeter and wiring diagram right now (and the Fiat had lots of ground/resistance problems).
The issue with the speedo is more of an irritant. I am guessing that it is the speedo gauge itself and not the speed sensor because there is an issue not only with the speedometer needle not reading accurately/bouncing around -- sometimes it does it continuously, other times it settles down after driving it a while -- but also with the odometer, so my issue is with the whole speedo gauge in the instrument cluster.
Does everyone agree with this or could it be the speed sensor? (presumably, the speed sensor also drive the odometer and trip meter mechanisms as well?)
Can these be repaired or do I need a new cluster? Haven't taken it out yet, but Haynes says the cluster is a one-piece integrated unit.
If so, is the 944 cluster a plug-and-play as I have four of those and long-term will only need two? Or is there someone that fixes these clusters relatively cheaply?
Otherwise, I love the 924 -- I have always wanted one since I was a kid -- and look forward to driving it a bunch once I have these little irritants sorted out, especially since it has great R134 AC while the 911T doesn't and the 928 does but it doesn't work yet (too many projects).
04-25-2018, 07:16 PM
#3
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The bounce in the speedometer is probably the cable. The 924S has a mechanical speedometer/odometer. The odometer gear is a weak link. Everyone says to only reset the trip when standing still to prevent breaking the gear.