DaleD

My gas engine all of a sudden wont idle. Engine readily starts and will advance to WOT but wont run below 3200 rpm. Any attempt to reduce throttle below 3000/3200 and the engine dies. Help please.

captinjohn

Look for a air leak in the intake area. Also the Idle jet could be plugged with crap. Capt,n

BadAzzMaxx

Get some carb cleaner, Crank engine and spray the carb cleaner on all the joints but do not let it go into the carb. If the RPM changes when you spray a spot you have a air leak there.

Milton

DaleD

Captj,

Thanks for your quick response. I am inclined to think that I may have an air leak because I removed and replaced the carburetor to strip it down and do a clean. If this is indeed the case, how do I go about identifying the location of the leak and the fix. Can I apply some kind of gasket sealer?

Is the idle jet the same thing as the low end needle?

captinjohn

You can use WD40 also to spray joints....it will change RPM at a leak. Capt,n

w8ye

My Feedback: (16)

yes, he was talking about the low speed mixture needle

Antique

My Feedback: (4)

A bad crank seal will do that...

MetallicaJunkie

is this done at WOT or just at idle.... this trick is new to me

BadAzzMaxx

Do it as slow as the engine will run.

Milton

DaleD

Thanks for all the suggestions. Iwill be checking to see if there is a leak and if the low end needle is clogged. What do Ido if there is indeed a leak? Is it as simple a replacing the carburetor gasket?

Antique

My Feedback: (4)

Depends on the location of the leak...Gaskets are easy, the crank seal requires dis assembly of the case and pushing the old seal or bearing out...
Some engines use a separate seal, some use a double sealed bearing...There are some sealed bearings that don't hold pressure well...The best for holding pressure are NSK with brown rubber seals as used in 3W and Zenoah engines....Found that out the hard way, a brand new black rubber seal bearing in a G26 still leaked, the engine would not run below 2600 rpm...Not enough crankcase pressure to pump the fuel at low rpm....

WRK

My Feedback: (2)

You are getting very good advice, thee guys know what thet are talking about.

karolh

Say Ralph, how is the Ford restoration project coming along.

Karol

DaleD

After much anxiety and further reading, Ifinally tried the carburetor cleaner test and sure enough the engine note changed when I sprayed in and around the area towards the rear of the carburetor insulator block(my engine has carburetor mounted on the right side looking out from the cockpit). Having read a post by Jody in the DLE20 thread that careful application of a thin flim of sealant to the insulator block and gasketswould address the leaking issue, Iremoved the carburetor and applied some high temperature silicone. The carburetor was replaced and left to set overnight.

While Ihaven't done a further carburetor cleaner test, I am happy to report that when I started the engine this morning I was able to reduce the idle to below 2300 rpm which Iunderstand is not bad for an unbroken in engine. Will provide further updates later this evening when Itest with carburetor cleaner.

Thanks again for all your help.

karolh

Never knew about the carb cleaner leak detection test before. Now ain't this forum a great place to hang out.

Karol