Knock, Knock, Whos There? Help!

[deathraider6996]

Alright guys, I finally have my car in Arizona with me! About a month in and im having the worst issue we've run into. first, and foremost, ill give you some details about the car. 1987 Buick T, 146XXX Miles, PT-51, hotwire, built trans, 60lbs injectors, vigilante TC, rjc pp, dutt neck, stock bottom end, stock heads, and even stock head gaskets. there are a few more item but i wont bore you guys any more.

The issue! I was driving home last saturday night. I brake boosted at a light by my house, did a 10 psi launch, it went well, until the scanmaster started showing knock. I could also hear the knock, which sounded more like a tapping/ticking. Oil pressure was normal. I limped it the remaining mile to my house. once at the house i began looking for the issue. It sounds like it is coming from the top end on the passenger side. Kind of hoping for a broken rocker, i pulled the valve covers. I didnt find anything out of the ordinary while in there. I started it with the valve covers off to watch for a possible wiped lobe, I couldnt really tell. All the pushrods were spinning. I pulled the rockers for a closer look. nothing out of the ordinary. I pulled the pushrods and they looked fine. I rolled them on my bench and none seem bent.

I checked the flex plate next. All the bolts were tight and the flexplate had no visual signs of cracks.

I checked the compression and all six were within +/- 5 of 120, which I think is good for how old and how many miles are on this motor.

Oil is not milkshaked. oil level is fine

During this inspection, i noticed a leak in my radiator. Ordered an fbody aluminum radiator.

 

[Steve Wood]

did you pull the hose off the turbo inlet and check to see if the blades are spinning freely and not touching the housing?

Is it still ticking? 

Pulled all the plugs to see if they look normal?

O2's etc look normal

[Steve Wood]

run your hand along the seam with the block below the plugs to see if you feel any hot air coming out from a blown hg?

[larrym]

Could it be a exhaust leak?

[deathraider6996]

did you pull the hose off the turbo inlet and check to see if the blades are spinning freely and not touching the housing?

Is it still ticking? 

Pulled all the plugs to see if they look normal?

O2's etc look normal

blades are spinning freely and not touching

i imagine it is, when i pulled the spark plugs i broke one, so i wont be able to run her tonight until i get new plugs. plugs all lok the same and are brown. they look normal.

i havent checked the o2s or looked at them when i was diagnosing.




Ive had exhaust leaks before and it doesnt sound exactly the same but close.

IDK if i said this in my prior post but the knock was constant with the rise in rpms. the knock was 0 or very low when at idle.

[deathraider6996]

run your hand along the seam with the block below the plugs to see if you feel any hot air coming out from a blown hg?

I will have to get to that test when i get some spark plugs.

Thanks Steve

[Steve Wood]

if the pushrods were turning, you can pretty much discount a bad lobe.  I am thinking it pushed a head gasket.

Problem with compression or leak down checks is that they use about 100 psi of pressure in the combustion chamber and may not show the leak as readily as several hundred psi of combustion leaks will.  this is where we could use an electronic stethoscope to find the area where the tick is coming from.

[deathraider6996]

I will check out the head gaskets once I get it running. Avila said there was a tester that checks for exhaust in the coolant. What are your thoughts before I pay 50$

Another question though, should I be able to move the pushrods up and down and spin them by hand?

Sent from my SM-N910T using Tapatalk

[Steve Wood]

the tester is very handy, but, I don't think you need it yet.  Usually, it will try to blow the coolant out into the reservoir.  I am thinking about what is ticking right now.

When the engine is first turned off, the pushrods will be stiff and hard to turn.  As they set a bit, some will probably be easier to turn..those that are on closed valves, anyway.  there should be no vertical movement ever when the engine is off.

[larrym]

what about huffing out the breather if the gasket was blown into the lifter valley.

[Just a Six?]

A few years ago I had a loud tick that went up with RPM & was loudest from under/around the Turbo cover. My Crank Sensor was somehow moved & rubbing but it sure sounded like it was the top end & not underneath until I finally stuck my head under the car. 

[good2win22]

A few years ago I had a loud tick that went up with RPM & was loudest from under/around the Turbo cover. My Crank Sensor was somehow moved & rubbing but it sure sounded like it was the top end & not underneath until I finally stuck my head under the car.

I had the exact same thing on my white T

[Steve Wood]

good idea...if it is rubbing, it could make the car misfire

[deathraider6996]

How would one go about checking the crank sensor?

I finally have the fbody radiator in and now i just need to delete the oil cooler lines. I will fill it with oil and coolant then put the plugs back in to check the headgaskets.

[Steve Wood]

http://www.vortexbuicks-etc.com/cranksensor.htm

make sure the sensor is centered so that the blades on the damper are are in the center of the sensor slot on all three blades and makes sure the sensor is not loose in its bracket.  turn the damper and check that all three blades go thru the center of the slot.

Then crank the engine and watch the damper move thru the sensor while idling to see if you see any contact or hear a noise at that point,.  Have someone rev the engine while watching the balancer.  Make sure the crank does not move backward or forward when this happens and so that the blades move and hit the sensor...