Chainsaw Repair

Husqvarna - Stihl - Poulan - Jonsered - Dolmar chainsaws and more => Stihl => Topic started by: ed on March 31, 2012, 12:55:02 pm

Title: Stihl HT 75 Flooding
Post by: ed on March 31, 2012, 12:55:02 pm
Hi, Have a Stihl HT 75 Pole saw that I let sit too long. Now it floods immediately when trying to start. I took the carb apart, cleaned everything put in fresh gas but no help, I noticed though a sealant? around what looks like some kind of pressed in plug was coming off. Don't know if this was just excess or is a problem. Found a rebuild kit and or a gasket kit but I,m thinking new carb. Anybody have any insight or advice? Thanks...Ed
Title: Re: Stihl HT 75 Flooding
Post by: 660magnum on March 31, 2012, 03:49:56 pm
You have seepage from the pump side of the carb past the needle and seat of the metering valve into the metering chamber of the carb.

In other words, the metering needle is not holding. This could be caused by a stiff metering diaphragm?

You may try to tighten the plug to see if it stops the leak but I doubt that is your problem?
Title: Re: Stihl HT 75 Flooding
Post by: ed on March 31, 2012, 04:43:36 pm
Thanks for the reply 660. The tip on the needle seemed flexible. Hard for me to judge. Found some opinions on leaking "Welch" plugs which is what apparently what I was refering to in my initial post. They say it can be sealed with nail polish? I guess the ethanol in our new and improved gas formulations eats the origional sealant. Wonder how JB weld would hold up immersed in gasolene. New carb on ebay~$45.00 and never store with gas in the carb? Kind of a pain to do that to all my seasonal / infrequently used / collection of tools. ( 15+ 2 strokes) I do use Stabil and have had good luck with it. Maybe this one was just due to fail and wasn't bad gas as I initially suspected. Anyone else have good storage tips? Thanks....Ed
Title: Re: Stihl HT 75 Flooding
Post by: 660magnum on March 31, 2012, 06:06:01 pm
My storage tip is to never let it rain on my tools.

When I get done with them, I put them away with the gas in them. I've been doing that for more years than I care to remember. Back in the late 50's, I would see a little mud in the carbs but not in the last 40 years. I never had any trouble leaving gas in the carbs. I have trouble with filter fuzz in the carb screens sometimes.

I have to replace a metering diaphragm every once and a while. I have not experienced any check valve flaps curling up on the pump diaphragms.

I have a lot of yard tools and chainsaws.

I must be lucky with good gasoline in this area?
Title: Re: Stihl HT 75 Flooding
Post by: Al Smith on March 31, 2012, 07:41:36 pm
Nail polish goes back decades for use as a sealant .

It's doubtfull the welch plugs are leaking .Most likely it just needs the carb rebuilt .You'll get maybe 4-5 years out of a rebuild if you run the tool on a regular bassis .Maybe 2-3 if you don't .The ethanol attacks the buna-n material the carb diaphragms and check valves are made of .Makes them stiff as cardboard .

A rebuild kit is usually pretty cheap .