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85 won't start when hot

My 85 Jetta 1.8L auto transmission won't crank when it's hot. On hot days, or when we drive far enough to get it quite warm, after it's shut off, it has to cool down for 20 minutes or so before it will start

I need to be clear here: The starter doesn't turn over at all. We hear a solid thump under the hood when the key is turned to the start position, but nothing more. The starter was replaced about 10,000 miles ago, and I've checked all the underhood wiring I can see. It's not the transmission interlock, I don't think, because of that solid thump that sounds like a solenoid throwing when the key makes contact. Likewise, I don't think it's the ignition switch electrical part, because of the same thump.

It probably needs yet another starter, but I can't figure out why it only does this when the car is fully warmed up, or in the summer any time the temperature is up over 75 F.

Any ideas?

Pat Moore

Reply to
Pat Moore
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Jim B.

Reply to
jimbehning

Possibly missing heat shield to the starter. Possibly engine running too hot. Possibly bad starter. What brand reman was it? Possibly bad wiring to the starter or poor ground conections. This can sometimes be overcome with a starter booster kit. This kit usually is a relay that supplies power from the battery bypassing the ign. switch and interior wiring. It almost sounds like a poor Battery Positive connection at the starter.

later, dave Reminder........ Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you are a mile away from them, and you have their shoes. Frieda Norris

Reply to
dave

Weak battery. When the starter is hot it takes more juice to get it going. This is more prevalent on automatic A2s too because of the starter location being closer to a heat source.

Reply to
Matt B.

Forgot to say...also check and make sure your 12V positive battery lead to the starter is in good shape as well as the main ground cable from the battery to the chassis (or maybe it's the engine...I forget offhand where it goes to). If they're bad replace them...if they're good, just make sure the connections are nice and clean.

Reply to
Matt B.

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