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Heat soak in a car?

used to have a problem with “heat soak” with an outboard motor. have a coworker that has a car that won’t restart on a hot day. can you get “heat soak” in a car?? gonna say its a 12 yr old buick something. v6, has happened a few times. if so, how to fix. thanks!!

FYI hot air, hot engine evaporates gas too quick “heat soak” I guess…

Yes, heat soakback can cause problems with a variety of systems…fuel, ignition, etc. Sometimes a bad coil won’t fire when it gets hot. Only way to trace it is, next time it wont start, check for basics like spark, etc.

Heat soak used to commonly cause vapor lock, back when we had carbs and lower-pressure fuel pumps. These days it can be a sign of electrical issues as @jesmed mentions, or maybe a weak fuel pump or leaking fuel injector allowing vapor lock.

I filled up my 460 powered 73 Lincoln that wouldn’t start for a while afterward. I poured a bucket of water down on the starter side of the engine and it spun right over and started. I then made a shield for the starter, attached it to the exhaust pipe and fixed the problem. I’m good when I want to be.

Thanks for the comments. I do know that fuel pump was recently replaced. here is the latest scenerio…
car sat in sun till noon drove short ride home for lunch… 1 mile… parked in driveway… wouldn’t start 20 minutes later… car started 3 hours later after sitting…

Will it crank or “turn over”? If it won’t, this is a common failure for starter motors–they will crank fine when cold, but once they heat up, will either not turn or turn the engine very slowly, all while drawing a lot more current than normal from the battery, which of course heats the starter up more.

starter does crank no problem there.

There is this starting problem specific to Hondas where the starter relay won’t work in a hot interior. There is another one where the engine to body ground needs cleaning. It doesn’t happen often.

Any device with a coil, including the ignition coil pack or an igniter. Without knowing what model Buick you have it’s a bit tough to ascertain if you have a distributor based system or COP.

The 20 minutes nofire combined with thestarting right up after sitting clearly suggests heat soaking. The areas areoundand inside your cylinders are much hotter than the temp showed by the temp gage. When you shute the engine off, the coolant stops circulating, the fan stops turning, and that heat begines to propogate out the sides of the engine and raise the underhood temperature. In your case you have a device breaking down as the heat rises. I’m gonna wildly guess a coil pack or igniter.

First step, check when this happens and see if you have spark.

Post back.

Great info… I will be back sometime with car year model engine info…
car is on its last leg, retirement looms and coworker is looking at a big insentive. new car in future…
again really great info though… educational…

OK, lets keep this going… car is a 95 OLDS delta 88 3800 enigine not supercharged. gazilliion miles…
distributor or COP??

Distributor. But not the same car you started the thread with.

Sorry about that M bike. wasn’t sure myself till I looked at it! car is original owner. 17 years old. I’m gonna guess everything under the hood is original. beside basic maintenance. Considering the possible heat soak problem,(very good explanation you gave by the way!!) what would could be replaced with an eye on cheap and easy. Aftermarket or junkyard. thanks again…

I thought that the last year for a distributor on these engines was 1985. After that, it was a coil pack with wires.

I stand corrected, The years pass quickly.

As to replacing components with aftermarket or junkyard replacements, I’d be inclined to stick with aftermarket and avoid junkyard. The reason things with coil windings become heat sensitive is because the dining wire is coated with a varnish-like polyimide-amide insulation that, while tenaciously bonded to the underlying wire, has a different thermal expansion coefficient than the copper wire. Over time, as the wire expands and contracts due to heating and cooling, the insulation becomes work stressed from being expanded and shrunk repeatedly and it develops cracks. Then when the device gets heated up, th ecranks open up and windings short out. This effectively reduces the performance of the coil until it no longer can induce (or create as a result of induction) sufficient current to do its job.

Boneyard devices will very likely have been subjected to the same conditions. Since the coil from one '95 Olds 88 will likely have been produced pretty much exactly like the one in another '95 Olds 88, it may be suffering the same fate. And you haven’t experienced your full potential to create expletives until you’ve tried to fix a car by swapping out components and the new component has the same problem as the old one…sending you on a wild goosechase up other avenues.

With a healthy federal retirement incentive on the horizon, this vehicle may end up in the boneyard soon. Great educational info.

Congratulations on your upcoming retirement.
And thanks for the compliment.

COP = coil over plug. This system uses no distributor. Each plug has it’s own coil. A 95 Olds probably uses a distributor.

Buy a “Test Plug”…It’s a spark plug with an alligator clip attached to it…Use it to test for spark when it won’t start. If you see no spark, replace the ignition module inside the distributor…If you DO see spark, then the problem is lack of fuel to the injectors…

no retirement in my future. this car is a co workers. I’ll be horsing the mail till I’m dead.
When I do have a problem, this is the first place I stop! Thanks again.

Actually, I think a 95 Olds would have distributorless ignition, but use a coil pack with a fairly conventional arrangement of plug wires. My dear departed mom’s '92 Buick was like this, as is my '94 Chrysler. My gf’s falling apart '98 Honda does have COP, but I think this was pretty much the first year manufacturers were doing this.

If the starter cranks normally, but the engine won’t ‘catch’, then it either isn’t getting spark or fuel. If you determine there is no spark, I’d bet on an electronic module failing when it heats up, or possibly a relay if the ignition system is fed through one. If you have Coil-over-plug ignition, or even a coil pack, it’s unlikely that enough of the coils would have failed for it to not start.

If no fuel is getting to the engine, it could be the fuel pump is going bad. The symptoms described are pretty common for a failing in-tank fuel pump. You can listen at the tank while someone turns on the ignition. You should hear a “whizzing” or high pitched whine for a couple of seconds when the ignition is turned on.

Another possibility is if the vehicle is new enough to have a transponder key and anti-theft system, it could be disabling the engine due to a malfunction.