Strange angle and noise from drivers side exhaust

Texasdoc · #1 (**permalink**) 05-19-2016, 03:37 PM

Not sure what is going on here. I tried going to a throttle body EFI system, but never could get it working just right.

At one point while I was driving, the system did not turn on the fan and the motor got to about 240 degrees before I noticed it was overheating. It was only that hot for less than 2 minutes. Turned it off, let it cool, then drove home. While driving home the heat was max 210 since the fan wasn't working but I was moving.

At another point I thought I got some bad gas vs plugged fuel filter but eventually found a bad coil. This caused erratic studdering until I figured it out then replaced the coil.

At some point during all this I noticed the driver's side exhaust pipe seemed to be rotated downward. The support bracket was previously horizontal, now it is angled about 15-20 degrees downward. Immediately after shutting it off a small amount of steam came out the exhaust pipe. Then next morning a few drops of fluid (water from bad gas? coolant? raw, unburned fuel from coil not firing?) had dripped from the pipe to the garage floor.

I inspected the complete exhaust, everything looked fine. Headers to heads had a small exhaust leak, but nothing major. Headers to collectors fine, pipe all intact, just seemed to be rotated. Not front to back angled down, rotation around the centerline of the cylinder, exhaust tip pointing down more toward the ground.

Engine mounts tight and level. No significant geometry changes visible to the entire motor. Compression test of all cylinders shows 170 +/- in all cylinders. Leak down test <10% on cold engine - most were <5%, #7 was about 8%. All valves reset to 1/2 past zero lash (hydraulic roller link bar lifters) and all valve springs/locks/rockers look ok. Head bolts tight. Intake tight. Bell housing to block, transmission to bell housing, transmission cross member bolts all tight.

It doesn't appear to be leaking water or oil (few drops at the rear of the pan), no air leaks. Idles fine, drives fine.

Problem is that when driving, letting out the clutch, I get a squeaking sound coming from the drivers side pipe. High pitched squeak/squeal. Starts when the clutch first starts to let out and engage (engine power coming on) and continues for 2 seconds after the clutch is completely released.

At first I thought it was the mechanical throw out bearing since it is a squeak/squeal sound - like the bearing was spinning but not greased correctly and potentially failing. I got the bearing with the transmission and wasn't sure who made it. I just replaced the mechanical bearing with a hydraulic one from McLeod. Works great, clutch releases easily but the squeak is still there. Can't be the bearing - completely new style does the same.

Any thoughts on the rotation of the pipe or the squeaking sound? If it got hot enough to melt the heads and deform the head enough to rotate the pipe 15 degrees, I don't think the head would work at all - just a big blob. If the block cracked - same thing. Seems like it would have to be the exhaust but for the life of me I can't find anything wrong with it. I pulled and twisted to see if there were some failing welds but can't seem to get it to rotate back to where it was before. Gotta be the pipe, right?

Large Arbor · #2 (**permalink**) 05-20-2016, 04:55 AM

If it was me and since everything is running fine, I think I would elevate the car and check about every visible bolt including motor mounts, exhausts, and everything underneath. It could just be coincidental that it occurred at the same time. Seems to me these vehicles are subject to lots of vibration.

Phil

Texasdoc · #3 (**permalink**) 05-20-2016, 02:38 PM

I've had it up on the lift a few times. Can't find anything loose.

olddog · #4 (**permalink**) 05-20-2016, 04:50 PM

Quote:

Originally Posted by Texasdoc

At some point during all this I noticed the driver's side exhaust pipe seemed to be rotated downward. The support bracket was previously horizontal, now it is angled about 15-20 degrees downward. Immediately after shutting it off a small amount of steam came out the exhaust pipe. Then next morning a few drops of fluid (water from bad gas? coolant? raw, unburned fuel from coil not firing?) had dripped from the pipe to the garage floor.

Definitely not un-burned fuel; it would have evaporated. Steam and water would concern me, especially since it was overheated. I would pressure test the radiator. If it does not hold pressure, be careful with hydro-locking the engine. You could fill a cylinder and bend a rod.

Watching the water in the cooling system for air bubbles with the engine running would show a head gasket leak from the compression. An intake leak will not show on this test.

Intake gasket can pour water into a cylinder and the compression and leak down tests could look good. Is the worst cylinder on the side that the water/steam came out? The cylinder that is getting water may have enough water to wash all the oil away causing the rings to not seal well. If so squirting a little oil into that cylinder would bring compression back up.

The squeal could possibly be a vacuum leak. Intake gaskets twisted up during the over heat, may cause a vacuum leak squeal and a water leak.

The pipe being twisted has nothing to do with the engine, although the pipe may have move while things were over heated.

Dominik · #5 (**permalink**) 05-20-2016, 11:48 PM

I once had a slowly overheating engine. Always a bit low on coolant, but blamed it on heat, pressure cap, phase of the moon...

Tested all you did, only to be unable to crank it after winter storage one year. Took the plugs out, one was rusted and the cylinder full of water.

I had a leak in one intake seat. Just that winter this valve happened to be open and let water seep into the cylinder.

Looking back, this must have been the most untraceable water leak I ever had.

Texasdoc · #6 (**permalink**) 05-21-2016, 07:21 AM

Dominik, you said you had a leak in the intake seat - did you mean intake gasket? I got a new gasket and will pull the intake to replace.

Dominik · #7 (**permalink**) 05-22-2016, 11:55 PM

Morning Doc, I had a crack in the seating surface of one intake valve.

The motor would burn the minimum amount of water which entered the cylider every time that one intake valve was open during operation. Causing it to slightly overheat and lose water.

It was pure coincidence that over one winter that very valve was open and let water in.

I would guess you could track this failure by running the motor to pressurize the coolant system, stop the engine and turn it by hand to open one intake valve at a time and check the cyliders for water.

This could be a bit elaborate, because once the pressure in the coolant system is gone, the hairline crack would not be wide enough to let water through.

Or in fact, just pressurize the system like checking for radiator leaks should work.

I also once had a massive oil leak when I mounted a set of used heads with threads in the intake channel to hold down a rev kit. I didn't see those threads, even though it was very obvious.

Well, we are always clever afterwards :-)