Timing belt job has not gone well

[sdpatt]

I replaced the standard parts for the front end 60K service for a gentleman's 100,000 mile, '95 3.0L SHO today and the car still sits in my garage tonight. The parts installed are listed below. Everything seemed to go well with no real surprises found (one exception: see 5th paragraph). I even took pictures of the belt installation alignment and verified that the dimples, ridges and white lines on the belt were properly aligned.

1. Front main crankshaft seal (National)
2. Water pump (reman) and O-rings (A-1 Cardone, Fel-Pro)
3. Lower radiator hose (Motorcraft)
4. Timing belt (Gates T248)
5. Crankshaft position sensor (Wells gapped at .03")
6. Serpentine belts (Gates)

When we first started the engine, there was a solid tapping or clunking noise that had the rythum of a piston hitting something. There was also a misfiring cylinder. We shut the engine down within 5 seconds and I inspected the basics. Subsequent running and inspection found a weak cylinder #2 from the cylinder balance test. There was spark at all terminals of the coil pack. When each plug wire boot was pulled from the coil pack there appeared to be a strong drop in engine rpm indicating that the affected cylinder was getting spark and contributing to keep the engine running(???). A mechanic's stethescope located the engine rpm-related tapping noise to be strongest at the valvetrain area of the number 2 cylinder.

When the #2 plug wire was removed, the plug well had about 1.5" of oil. I suctioned the oil and removed the plug (AGSP32PP gapped at .046"). There was dampness in the cylinder, but not a puddle, just moisture on the carbon buildup on the top of the piston. Seems to be getting fuel.

I replaced the plug with a new AGSP32PP gapped at .044". I dried the oil from the plug boot (inside and outside). I did not confirm that there was spark at the plug. The plug wires were not the Motorcraft brand.

One thing that did stand out as odd during the service was when the timing belt was off and I was gapping the CPS. I slipped the damper on the crank enough to engage the keyway, but it was such a tight fit, I did not press farther than necessary. I used two hands on the damper to rotate the crank to check the gap on each shutter vane on the timing belt sprocket. Two times in the one revolution of the crank, it firmly bumped into something. Much more solid than cylinder compression. I was able to turn the crank after a few more seconds, but with effort.

My thoughts were that this is a non-interference engine. The current owner, a retired man who bought the car at 30K-ish miles, has not had the engine apart for either 60K service (timing belt was OEM, and valve gapping has never been done). Could there be a high-lift cam in the engine and I just bumped a piston into a valve?

I removed the upper timing belt cover and verified that the timing belt alignment was correct. With the crank damper white notch at the 0 degree mark on the lower timing belt cover, the dimples on the camshaft sprockets were at 12:00 and aligned with the ridges on the rear, metal timing belt cover.

I plan to dig into the valvetrain tomorrow for the upper end 60K to see if I can find anything amiss under the valve covers.

Please share you thoughts on this situation if you think you can help me tap into some of the massive amounts of collective SHO knowledge. Please help me determine if I have killed a SHO. This makes me feel sick.

 

[TimboSHO]

My thoughts were that this is a non-interference engine. The current owner, a retired man who bought the car at 30K-ish miles, has not had the engine apart for either 60K service (timing belt was OEM, and valve gapping has never been done). Could there be a high-lift cam in the engine and I just bumped a piston into a valve?

Even on a non-interference engine, strange things can happen. It's hard to give wisdom to someone who has infinitely more SHO knowledge than I, but I only turn the crank/cams with the timing belt on. I'm not sure if you usually gap the sensor with the belt off like this, but I like to play it on the safe side. I think that the best way to rule a bent valve out would be a compression and/or leak down test. Good luck!

 

[sdpatt]

Thanks for the feedback Timbo. I usually do not rotate the crank without the belt on either. I was checking all vanes of the shutter wheel because there were interference scratches on the outer diametere of the vanes from the previous CPS installation. I wanted to make sure they were all consistent at 0.03". I usually do that with the keyway out and just spin the sprocket on the cranksahft.

I will be opening up the valvetrain today for a closer inspection and a compression test is a good check of the valve sealing. Good suggestion.

 

[93rev2sev]

Yer a pretty thorough mechanic, Steve. I'm sure you will take the correct steps in diagnosis. I think you are right to dive in to the valvetrain. There might be something jamming the cam chains? Or any other type of debris under the valve covers. You might also realize that once the oil pump begins sucking, you might feel a bump. You will probably change the oil before you fire it up next, might as well try turning the engine by hand again with no oil to see if you can make out any difference in the feel of it

Of course, if you remove the plugs, and timing belt, and have no oil in the crank case, you will have a better shot at listening to the rotating assembly. Since there will be no compression or valve spring compression or fluid(oil) compression, the rotating assembly should spin freely...I know..this means taking the timing belt off again...

Edit... oh, and have the clutch pressed.

 

[matty]

.03?

.03 that seems close for the sensor is that right,you sound like a whiz but i did all of the same stuff the other weekend.crank seal,cam seals,timing belt,waterpump,etc but mine is a mtx and was glad it wasnt a atx.but i copied what phoenix project was doing or did and it ran great,but anyways my crank sensor i was told to gap at .76

 

[93rev2sev]

it's .03 INCHES on both sides. That's .06. Plus the thickness of the vane. So your .76mm(I know you didn't mean .76") sounds ok. Also, .03" is .96mm. So maybe you had a different feeler gauge. .76mm would be fine...a little tight...but it would work.

 

[matty]

ok

i was feeling a bit nervous

 

[SolidState]

is it possible that a small piece of carbon has broken off in cylinder number 2?

 

[SWM]

My 2 cents, I recently had a similar problem while reassembling my 94 ATX. After removing the rear valve cover a mangled peice of white plastic from the cam chain tensioner was wedged in the valvetrain.

 

[sdpatt]

Found the source of the rough running and tapping

This morning I started the valve gap adjusment procedure with a bit of nervous dread. The job went by the book with the removal of the intake. One of the things I do with the intake off before removing the valve covers is to swab the intake ports down to clean aluminum. The front bank cleaned up normally. It was on the back bank, on the number 2 cylinder's secondary runner side that I found the first evidence of something not right.

The white terry cloth rag sprayed with carb cleaner revealed a trace of brass colored metal flakes in the blackness of the oily residue being cleaned from the ports. Brass or copper; where could that have come from? The valve guides are silver colored. The valves are steel. The pistons and heads are aluminum. The cylnder walls are iron. And how did it get in the intake ports? The primary side valve was quite clean. The secondary side valve has a few more oily black deposits, like the rest of the secondary side valves.

I continued on and removed the valve covers. A quick inspection of the number 2 cylinder area showed no obvious problems. No loose parts stuck in the valve train, no thrown shims, no loose timing chain tensioners. Both tappets on the number 2 cylinder felt normal when depressed with the tappet compressor. I started the measure and repalce task of the gapping adjustment.

The engine showed excellent consistency of the gaps. most were at the nominal gap or one or two feeler gauge thicknesses on the large side of nominal. A handful were out of spec on the high side. The crank was turned to allow measurement of the number 2 cylinder (I had been somewhat avoiding this cylinder). The secondry side measured at .229mm (.009"), within range. The primary side measured, oh my, how many feeler gauges is this going to take, starting to double up the thick sizes, oh shit, .915mm. That explains the ticking noise. Houston, we have found the problem valve.

The primary valve would not hold intake cleaner on the valve with the cam lobe up. You could see it bubbling through. Blowing through the compression tester hose screwed into the spark plug hole found no resistance. With liquid on the valve, it could be seen that the air was easily escaping past the valve seat.

Phone calls to my SHO friends MikeD. and TexanTony brought possiblities of a bent valve or a broken spring. Mike offered to drive the hour from his house to help with tools and his time. Tony offered advice and said he would be there in an hour. Tony said we could check the valve spring tonight. He drove the hour from his home to chip in to help.

He quickly removed the cams from the rear bank head. We then filled the cylinder with nylon rope (Mike's suggestion) and hand turned the damper to raise the piston to compress the rope, ensuring the valve stayed up when the keepers were removed. With the intact valve spring in our hands, it was obvious that we were not holding the answer. The worst case became a reality - the valve stem was bent and the head would have to be removed to replace the valve.

The question is how did this happen on a non-interference engine with OEM cams and very few carbon deposits visible in the cylinders. Why only one of the two valves on that cylinder? Tony thought that some foreign object in the cylinder may have interfered with the valve. He offered to complete the head removal and repair service when his time allowed. He was just as curious to find out what caused this valve to be bent.

I believe that the valve was bent when the engine was first cranked to a start after the timing belt was replaced. We heard a solid clunking in those first few seconds. The clunk became a tapping after a few more seconds of running to disgnose the problem. This could not have been caused by a good thing. But what?

The story will continue after Tony has removed the head and seen what could have struck that valve. It will be at least a week before he can work this job into his schedule.

I want to take this opportunity to humbly thank Tony for his kindness and willingness to help when I was in dire need. Friends like that are a blessing.

Till the next episode....



P.S.: CPS gap = .03" = .762mm

 

[TimboSHO]

I have been waiting to see what you found on this. I guess that's not great news, but at least you have it diagnosed and you know where you're going. Very odd indeed to have only one valve bend on such a clean motor..... I would also be interested in what you may find inside the cylinder. Thanks for the update.

 

[93rev2sev]

Yikes. Well. I'm sure someone has a head laying around...

Hopefully the damage ends at the valve...but I understand your concern, how could the valve bend? As you mentioned...it is a freewheeling engine.

You don't have to wait...you can get the head off and inspect for further damage.

I guess the good news is...Whatever it was....it was brass? That bodes well for the cylinder walls. I'm throwing a guess out there...

Butterfly screw.

Edit...might as well have a look and see if any are missing...

 

[SolidState]

how is the owner taking this?

 

[sdpatt]

Quite well. The SHO is a second car and it has been in storage for three years. He wanted to get the maintenance performed before he drove the car from Dallas up to New York to leave it as his ride when he visits his mother. With the wrench work that he saw be me and Tony, I believe he thinks the car is in good hands. I will update hte topic when the verdict comes in as to the cause of the bent valve - if it can can determined.

 

[93rev2sev]

Anything? Waiting on baited breath here...

 

[rudedog]

I believe Tony's mom is about to have surgery, I think we'll all need to be patient and see what happens.(with her and the car)

 

[AREA 91]

Copper in the oil? Rod bearings.
Bent valve? Foreign object.

 

[sdpatt]

The verdict is in...

After Tony Huerta (TexanTony) removed the rear bank head last week, the cause of the bent valve was quite obvious. Tony said that the carbon build-up on the pistons in the seldom used SHO was so thick that the piston reliefs could not even be seen. When I rotated the engine by hand on the damper when the timing belt was off, I apparently pushed the carbon-domed piston into the fully open, number two cylinder intake valve. The carbon buildup under the secondary port valve must have been a bit thinner than that beneath the primary port and allowed that valve to escape without contact.

Tony alerted the owner to this condition and the owner elected to have Tony also remove the front bank head in order to clean the carbon from the pistons. As of my last contact with Tony, the rear bank head had been sent to the machine shop for refitting a new intake valve and a good solvent soaking was applied to try to loosen the carbon on all the pistons.

Tony should have no problem finishing the reassembly since he has a good deal more practice than I. This has been a humbling and expensive experience. Having replaced my wife's car's strut bearings two weeks ago, replaced my steering rack, tie rod ends, sway bar links (all under lifetime warranty ) last week, and just today flushing the power steering fluid and repairing a leak at the power steering fluid cooler, I am physically and emotionally tired of working on cars right now. I pray that the closing chapter to the story of the green 1995 MTX SHO ends with "and drives off into the sunset."

 

[sdpatt]

Copper in the oil? Rod bearings.
Bent valve? Foreign object.

That was copper in the intake ports and was likely due to the interference in the valve guide of the bent valve and the blowback in to the intake manifold through the unseated valve.