Cracked Intake? Fuel in EGR?

GT_Rich

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#1

• Apr 1, 2007

• #1

I've been battling an odd miss/tick/knock sound since my H/I swap last weekend. The noise comes only under load with the engine up to operating temperature. I posted previously and the response was lifters - but these are new. I only have 10 in-hg vacuum at idle. Today I gave up trouble shooting and starting tearing everything apart. I didn't get too far...

My upper to lower intake gasket (org 93 Cobra I bought off ebay) is saturated with fuel around the EGR port. I'm suspecting I have a crack somewhere in the manifold? I also should note that I sent this to Tmoss and had the lower ported to a 1250 gasket, and had the upper solvent tanked and painted.

Could the function of the EGR be causing this? I still have it all hooked up, but I'm debating removing it to eliminate another potential problem. What's involved in that?

Thanks in advance. I'm so tired of trouble shooting this! It doesn't seem anyone ever has input (whether it be here on stangnet or people I live near).

 

jrichker

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Pull the vacuum line off the fuel pressure regulator. Look for evidence of fuel leaking from the vacuum line that was connected to it. Start the car with the vacuum line disconnected from the fuel pressure regulator. Look for fuel escaping from the vacuum port. If you see any fuel or evidence of fuel there, the regulator is leaking.

 

GT_Rich

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What does the fuel pressure regulator have to do with fuel in my EGR passage?

 

jrichker

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GT_Rich said:

What does the fuel pressure regulator have to do with fuel in my EGR passage?

Click to expand...

After re-reading your post, it probably isn't applicable. Leaks in the fuel pressure regulator vacuum line will dump fuel into the intake manifold and it can show up in odd places.

 

GT_Rich

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#5

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Well, thanks for the reply anyways. FWIW - the FPR is a new Aeromotive adjustable unit, and I pull the vac line off of it all the time because that's the port I use to hook up my vac gauge. It's never been the slightest bit moist.

 

tmoss

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#6

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hmmm - that's what I suggested too, it's the only way I can think of to get fuel up in the top portion of the intake - I told him to check the vacuum lines too, especially if the EGR and FP regulator shared a vacuum line.

Try disconnecting the EGR vacuum line and run that way for a while to see if the gas continues to accumulate. YOu'll get a CEL, but you can clear that later. I can't see any way a crack in the intake would result in fuel in the upper portion of the intake.

I also said to check all vacuum system diaphragms for leaks, including the power brakes.

 

Mr. Rustypwnz

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#7

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never mind

 

GT_Rich

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#8

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Well, yesterday I had two people (one being a summit tech guy, the other being an old school engine builder) tell me that my sound is an intake valve not closing all the way - which would shoot fuel back up the intake. Both also said the only way to adjust stud mount rollers is with the motor running. So I'm going to try that tonight.

 

tmoss

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#9

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sure that could do it too, but I's think you could hear that all the time if it was tightened down that far......you'll see tonight - good luck.........

 

GT_Rich

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#10

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I readjusted all the rockers again tonight with it running. I ended up taking about half a turn out of all of them. STILL NO LUCK! I took it for a spin and get the same ticking once it gets up to temperature. This is driving me insane!

 

tmoss

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#11

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do you own a mechanics stethescope?

 

GT_Rich

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#12

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No - if you think it would help I'll go get one. I tried using a poor man's stethescope - a piece of 3/8" dia vacuum hose. Unfortunately, the noise only comes under load, so I don't think checking it while idling will do anything.

 

GT_Rich

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#13

• Apr 2, 2007

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I guess my next step in the process of elimination will be to remove EGR. After searching, I have a few questions on that:

1. Where can I block it off at? Between the upper and lower? If so, what do people use?
2. Do I just make a plate that caps off the two holes (behind the TB) that the EGR uses?
3. Finally, when people say to leave it hooked up (electrically), are they talking about the solenoid that switches vacuum on/off, or the EGR valve attached to the intake? (or both)

Thanks in advance,

 

tmoss

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#14

• Apr 3, 2007

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too bad it only happens under load - a poor mans stethescope is actually a long handle screw driver - place the balde on the engine part you want to listen to, put you hand over the end of the handle and press you ear to it - works fairly well.

Just pull the upper and cut a small piece of galvanized sheet metal to place over the small round hole in the lower to stop the gas from going to the EGR - leave the rest in place.