Harder to Crank After Heated up

I've noticed my 1915cc engine starts up easily when cold. However, after running it up to regular operating temp and stopping it, it seems to struggle at first when I restart it. The battery and charging system are OK. Could this be the effect of heat on the valves or si this normal?

Steve

Here's a little reading material with several suggestions specific to VW from a Type II guy:
http://www.type2.com/dakhlia/overheating.html
The topic is overheating in general. IMHO, the suggestions and the symptoms still translate pretty well to Type I engines.

Anybody who used the word "goop" in a technical paper can't be all bad.

Couple of reasons this happens. One is the effect that heat has on electrical components. Heat increases electrical resistance. This does factor into the amount of current that your starter will draw when the starter itself is "heat-soaked."

But the real issue is actually piston to barrel clearance. When your engine is fully hot, your piston and barrels swell slightly decreasing the gap between them. This makes for a very tight fit between the two. The tighter that clearance, the better the seal in your combustion chamber and the harder your starter must work to turn the engine. When your engine is hot, it actually has more compression than when it is cold. Normally when an engine is shut off, it stops with a piston on the combustion stroke. With a tight seal there is significant pressure in that cylinder that the starter must overcome.

If this proves a problem in warm weather there are a couple of things you can do to help yourself out.

1. The BEST thing you can do is swap out to a high torque starter. This generally eliminates the problem with no other mods.
2. Higher amperage battery especially if you are using a small low
amp battery.
3. Move battery close to starter or use very heavy cabling (which has less amperage loss than lighter cabling) can sometimes be helpful but is usually impractical on a speedster due to packaging issues.

angela

funny you should mention the batt cables. The cmc positive cable
gauge is one step above spaghetti. Another suggestion to the abov problem....All you connections must be 100%. At battery, starter
and frame ground. Good luck.

...
Don't forget the ground strap that goes between the frame and the trans. It's usually located at the front trans mount.

Greg B

Steven; Angela said it all; it's pretty normal with air-cooled VW's and I've experienced that with all I've had.

I've noticed the same thing with my car. But it is not a problem simply when the engine has fully warmed up. It only happens after the warmed engine sits for a good 20 minutes or so. If I turn off my fully warm engine and wait five minutes, it'll fire up fine. And even after 20 minutes, I find I just need to give it more gas to start up.

Thanks for all the responses. Good to see this is "normal" and that there are few alternatives to improve hot starts.

Steve

BTW another good alternative to checking engine temp would be an infrared thermometer. I use one for nitro & 2 stroke model cars and had not thought of using it on my Speedster's engine.

http://www.raytek-northamerica.com/cat.html?cat_id=2.3.5

or

http://store.autotoolexpress.com/pointh.html

Steve

The reason the hot-start problem is WORSE when you let it sit for a few minutes (15-20) is because of heat soak. When the engine is running, it pumps air all around. when its off, of course, it does not. So there is nothing to cool all those metal parts. Until they lose heat, they actually continue to slightly swell (tightening your tolerances). Once they actually start cooling, the metal contract to its starting point.

It's like a hot potato. As long as you move it from hand to hand real quick, you can deal with the heat. But try holding onto it for a while... That's "Heat Soak".

angela

In an ironic twist of fate, I killed my lawnmower this weekend by overheating it. Turns out you have to add oil occasionally. Now I'm going to have to make a dump run.

Cory, I hope your lawnmower wasn't illegel. They're getting pretty strict above hiring so be careful...

As it died, it whispered something about Hoffa. ... Wanna help me with the dump run?

...inside sources tell me that Hoffa was actually placed in the 'witness protection program'. He now makes a living disguised as Oscar Meyer and drives the Weinermobile!

And contrary to the 'heat soak' phenomena experienced by our Speedy's air-cooled engines, the Weinermobile engine is actually hard to STOP once it gets heated up!

Jim, does it "plump" when it cooks?

Replace starter with a high tourque unit.