Does anyone have a tool to find a vacuum leak? (1 Viewer)

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saltycoconuts

saltycoconuts

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Feb 10, 2017
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Hello,

I’ve been experiencing a vacuum leak that I’m not able to track down. If anyone can help me find it and fix it that’d be awesome!

Thanks, Alika
 
What steps have you taken? What engine?

Have you tried the carb cleaner test?
 
BreckenridgeCruiser said:
What steps have you taken? What engine?

Have you tried the carb cleaner test?
Click to expand...

Unaware of carb cleaner test, I’ll look it up.

I’ve replaced all vacuum hoses.

It’s on a 13bt so because there’s a leak my engine won’t shut off from the VSV. I did have a leaking intake gasket which I thought was the issue, but after replacing it I still have a vacuum leak. (No boost leak though!!!)
 
Isn't that a diesel? Diesels don't pull intake vacuum like a gasoline engine. They typically require a vacuum pump for any vacuum dependent accessories or functions.
 
elripster said:
Isn't that a diesel? Diesels don't pull intake vacuum like a gasoline engine. They typically require a vacuum pump for any vacuum dependent accessories or functions.
Click to expand...

Yup and with that vacuum leak when I turn my key off and pull it out the sucker is still running since it doesn’t have a closed system:cry:
 
So is the pump creating enough vacuum?
 
Have you checked your vacuum canister? 13bt engines need a storage canister where vacuum is stored...
 
So I looked at the diagram... Have you checked the diaphragm at the top of the intake is good? The actuator of the butterfly valve in the intake is operated via vacuum from the vsv on the low side of the left side of the block... Trace all of those hoses and make sure they are in good shape...

Do you have the 13bt repair manual with the diagrams?
 
Also, where are you located? I could take a look if you were nearby...
 
BreckenridgeCruiser said:
So I looked at the diagram... Have you checked the diaphragm at the top of the intake is good? The actuator of the butterfly valve in the intake is operated via vacuum from the vsv on the low side of the left side of the block... Trace all of those hoses and make sure they are in good shape...

Do you have the 13bt repair manual with the diagrams?
Click to expand...

Yes on the manual and interestingly with the butterfly valve on top prior to changing my manifold gasket when I’d close it by hand it wouldn’t shut off. Now I’m able to shut the engine off by pulling on the lever. Also, when I pinch the hose coming from the VSV (I’ve relocated the module to the firewall for easier access and to keep it dry) I’m able to shut off the engine. All hoses were replaced with new oem ones when I rebuilt the head. I did a smoke test and can’t seem to find any leaks, might have been to late at night with not enough light so I’ll try again in the morning. I’m in Chula Vista btw, feel free to swing by.
 
That makes sense. If your manifold gasket was bad, air would sneak by there and continue to feed the engine. Even with the butterfly valve closed the engine would be getting enough air to continue running.

I personally would make sure that I'm getting vacuum to that diaphragm at the butterfly valve. I would check to make sure that the valve is closing fully when vacuum is applied. It's a simple mechanism that could be failing and is easy to check before you start digging into vacuum source.

Technically you could start at either end, the butterfly valve or vacuum source, but since you're not seeing the engine shut off I would start at the butterfly valve end because your vacuum system could be fine but just not closing the valve...
 
Is your VSV working?? They can crap out. Report back.
 
I’m guessing either It’s the butterfly or the VSV as well. Just ordered a new VSV; should be here in a week or two (if it’s actually in stock). Interestingly when I have a vacuum hose connected to the butterfly valve, under engine acceleration it causes the valve to close, so right now I have it closed and I just turn the truck off by hand. I have noticed hard brakes and a stiffer than normal clutch.
 
^^^ important info...

The butterfly valve should be able to close at idle vacuum...

Try sucking on the hose to the valve and see if it leaks... it should hold pressure with vacuum... If it slowly releases, then you have a bad diaphragm.

But, the hard brakes and clutch (assume this is a 70 series with assisted clutch) means that you may have a leak in the system, or worse, a failing vacuum pump... Does this engine have the vacuum pump on the back of the alternator?
 
BreckenridgeCruiser said:
^^^ important info...

The butterfly valve should be able to close at idle vacuum...

Try sucking on the hose to the valve and see if it leaks... it should hold pressure with vacuum... If it slowly releases, then you have a bad diaphragm.

But, the hard brakes and clutch (assume this is a 70 series with assisted clutch) means that you may have a leak in the system, or worse, a failing vacuum pump... Does this engine have the vacuum pump on the back of the alternator?
Click to expand...

Yes vacuum pump is on the back of alternator. I don’t think it’s going bad because I had the alt and pump rebuilt over a year ago. I’ll see the steps to diagnose the diaphragm according to the manual. I did a smoke leak test just now and the only small leak I found was actually at the VSV. Looked like it was leaking internally.
 
I do have a vacuum gauge if you guys need to borrow...
 
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