eldo97 - how to check plenum /vacuum leak

john19990 · #1 (**permalink**) 12-31-06, 12:49 AM

Can you please share how to check plenum or how to perform vacuum leak test. My eldo 97 stals when cold start but works perfectly when warm. Where is the plenum? How to test. Where are the 6 plenum nuts?

Thanks
John

**Ranger** · #2 (**permalink**) 12-31-06, 04:30 AM

The plenum is the intake manifold. Spray some Brakleen or carb cleaner around the perimeter and listen for an RPM increase. That's where the leak is.

davesdeville · #3 (**permalink**) 12-31-06, 04:32 AM

The plenum is the part of the black thermoplastic intake manifold that all the runners connect to. The runners are what allow air to flow to the intake ports from the plenum.

If you want to see if there's a leak present and find it's general location, get a propane torch. Keep it unlit, but open it up so propane flows out. Then aim it at places you think the leak might be. If the idle smooths out or changes noticeably, you found your leak.

john19990 · #4 (**permalink**) 12-31-06, 10:41 AM

Thanks so much for the replies.

Is manifold intake the same that is opened when cleaning TB? I want to check the plenum bolts if tight. I understand that there are 6 plenum bolts. Honestly I dont understand which is the manifold intake. I tried to search any picture of the manifold intake but could not. Any description of intake or picture will help. Thanks again.

John

**Ranger** · #5 (**permalink**) 12-31-06, 03:50 PM

There are some pics somewhere, but I cannot recall where. The TB is bolted to the black thermoplastic intake manifold aka plenum. Remove the silver beauty cover and it will become very obvious.

WarrenJ · #6 (**permalink**) 12-31-06, 06:49 PM

Wouldn't a minor vacuum leak cause an *increase* in RPM?

John19990, I'd be interested in knowing what has steered you to the plenum as a source of your problem.

Is it hard starting when cold?

Regards,
Warren

**Ranger** · #7 (**permalink**) 12-31-06, 08:59 PM

Yes, that's true Warren. Just guessing here, but maybe on a cold engine it leans it out too much to keep running.

john19990 · #8 (**permalink**) 01-01-07, 01:00 AM

Warren,

My Eldo 97 stals after cold start once every few days during the first couple of miles on traffic light. Once engine is warm, it runs great. Once of the posts on this forum something like "rough idle problem solved" indicated a similar issue that was resolved by tightening the loose plenum 6 nuts. I understand that this individual had a similar problem of cold idling. I thought that I might have a similar problem so thought of checking the plenium 6 nuts.

Thanks
John

davesdeville · #9 (**permalink**) 01-01-07, 04:37 AM

Can we stop calling the whole intake manifold the plenum? The plenum is the open area of the manifold, the runners are the rest, it's not just the plenum..

WarrenJ · #10 (**permalink**) 01-01-07, 04:45 AM

Quote:

Originally Posted by davesdeville

Can we stop calling the whole intake manifold the plenum? The plenum is the open area of the manifold, the runners are the rest, it's not just the plenum..

Okay, can I be the first to stop calling it that? Please consider it done.

Regards,
Warren

davesdeville · #11 (**permalink**) 01-01-07, 06:38 AM

You can be the first to stop calling it that, I applaud you for your effort and will give you some rep points

clarkz71 · #12 (**permalink**) 01-01-07, 04:54 PM

Here's the manifold. There are 5 bolts on each side, the two inner bolts on each side double as the hold downs for the beauty cover. NOTE: Be advised, the torque is only 89 inch lbs or (7.4 ft lbs)