If Compression tests fail?

[RI-SHO]

Ok I found out today that my timing is perfectly in spec nothing wrong everything is correct.

Now he said he ran a partial test and it seemed like there is a leak somewhere because he barly got a reading. Tommorrow he will be doing it correctly to each piston and give me the reading for me to post here. Now his assumption right now is that its a bent valve or something with the valve train itself if air is still being blown back through the intake.

Now isnt the SHO a non-interference engine with stock camshafts? If this is so what and how could a valve have bent the way it did so suddenly?

Doug has helped me by telling me to check the EEC/PCM wiring harness because this was his problem on a "steal" of a SHO. I have also been told to check the spout connecters as well but also read they can throw a code and I am receiving no codes with my current situation.

BTW one last question, where exactly is the fuse box in the engine compartment if the SHO even has one? Or is the panel in the interior the only place where fuses are in the SHO?

<small>[ October 17, 2002, 10:44 PM: Message edited by: RI-SHO ]</small>

 

[twr]

RI-SHO,
No way to bend valves in SHO motor - unless you have a ton of carbon on top of the pistons. The thing to think about - it takes an impact of some sort to bend valve(s) - so how would it have a bent valve(s) in the first place if the timing isn't screwed up (no way the piston can hit valves if the timing is good). Are you sure your mechanic is certain on the timing issue??

 

[RI-SHO]

He showed me the white crank line and markings on the cam on top and it looked exactly how it did in the pics Scott took of how to set timing correctly.

Only weird thing maybe b/c it was at TDC is the left cam mark was at about 11o'clock and the right one at almost 2-3o'clock. So if I read Scott's post right they both should be equal? Or set to 12o'clock?

 

[Yamaha V6]

He MAY have done it wrong then:

(forget TDC for a second)
line up the cams & crank:
12:00 left cam
12:00 right cam
5:00 crank

Line up the cam ids to the stamped mark on the metal rear timing cover, line up the crank id on the crank gear to the mark on the engine, then line up the marks on the timing belt (correct ones for 3.0L, writing legible from standing on the driver's side).

Also, it IS possible to bend a valve, or to have a valve stick open - look at the 60k page at www.neshospecialists.com to see one way it's possible to wipe out one valve. You could break a valve spring, your could have thrown a shim, etc.

Good luck Edien. No compression sounds like a) timing b) broken valvetrain or piston ring c) guy not doing it right.

<small>[ October 18, 2002, 09:32 AM: Message edited by: Yamaha V6 ]</small>

 

[sdpatt]

RI-SHO:
He showed me the white crank line and markings on the cam on top and it looked exactly how it did in the pics Scott took of how to set timing correctly.

Only weird thing maybe b/c it was at TDC is the left cam mark was at about 11o'clock and the right one at almost 2-3o'clock. So if I read Scott's post right they both should be equal? Or set to 12o'clock?

In that last paragraph, what marks were at 11 and 3 o'clock? The white marks on the belt or the index marks on the camshaft pulleys? If it is the marks on the belt, then that is not a concern because they will only help you install a new belt. If you are referring to the index dimples on the pulleys, then you have a mistimed engine and have found your problem. Which was it?

 

[RI-SHO]

sdpatt:
In that last paragraph, what marks were at 11 and 3 o'clock? The white marks on the belt or the index marks on the camshaft pulleys? If it is the marks on the belt, then that is not a concern because they will only help you install a new belt. If you are referring to the index dimples on the pulleys, then you have a mistimed engine and have found your problem. Which was it?

The index marks on the cam itself, the left was at 11 and right at 3, dont know if it was at TDC but thats what I saw.

Is there a possibilty it could be crank cancer as Erik says and it is my crank key?

I am going now to the mech i'll post again with the compression test results.

 

[RI-SHO]

WOW!! eek!

He got my baby running just not idling now, which he narowed down to the knock sensor which I already have on order and should arrive on Tue.

With a bad knock sensor will the timing be ******** and RPM limited to 5K? Is it a default?

And doesn anyone know of any parts store which would stock this knock sensor?

 

[sdpatt]

Edien, your car's problem was mistimed camshafts. As to how they got that way I would suspect the timing belt tensioner was not set properly or the tensioner spring has failed. If the belt wasn't floppy loose, the tensioner was probably not set correctly at the 60 degrees BTDC position as required by the procedure.

The only way for the cams to get out of synch with each other is either the belt was installed improperly or the belt has slipped teeth because it was too loose. Even if the keyway on the crankshaft was not present, the cams will not changed position with respect to each other. They would change position with respect to the crankshaft though.

You must disassemble and inspect the timing belt tensioner, the crankshaft keyway and the timing belt itself. Check the spring load on the tensioner pulley and make sure the bolt was properly torqued to hold it in position.

On reassembly, make sure the crankshaft is set to 60 degrees BTDC (yellow mark on the damper at the "0" on the lower timing belt cover tab when the tensioner is torqued down. The belt should be replaced since it has slipped on the pulleys and you cannot guarantee its condition. For the cost of a $35 Gates T248 from RockAuto.com, you can't risk it.

For the knock sensor, get the Wells (for a '91 SHO) SU2027 from AutoZone for $19.99. Any auto parts store should have one brand or another that fits the SHO.

 

[shojuan]

RI-SHO:

sdpatt:
In that last paragraph, what marks were at 11 and 3 o'clock? The white marks on the belt or the index marks on the camshaft pulleys? If it is the marks on the belt, then that is not a concern because they will only help you install a new belt. If you are referring to the index dimples on the pulleys, then you have a mistimed engine and have found your problem. Which was it?

The index marks on the cam itself, the left was at 11 and right at 3, dont know if it was at TDC but thats what I saw.

Dude, your cams are totally off! A proper reinstallation of your timing belt should cure your woes 100%! When the harmonic balancer mark is aligned with the 0, BOTH cam sprocket dots should align with the 12 O'Clock cam timing case lines. Jump for joy, get that timing belt removed, the cam sprockets aligned properly, and a new belt put on properly and enjoy your SHO! Just in time for winter nap time for the new car!

thumbs_u

Rick

 

[RI-SHO]

I'll have to do it on my next day off but i'm pretty sure since it does not pop or backfire from the intake anymore whatever timing issues it had were resolved.

What do I need to remove the upper timing cover? So I can visually check it then get into the crank if the cams are off again.

So I am wrong by thinking that I am being limited to 5K b/c of just the knock sensor? Or could this all be the cause for now?

 

[SHOTIME]

didnt you have a 60K at SHOmasters??

<small>[ October 18, 2002, 07:08 PM: Message edited by: SHOTIME ]</small>

 

[RI-SHO]

The rest of my 60K was done last year at Herb Chambers to the tune of $1,300 and for some reason they couldnt find out where my oil leak was. When Erik founf the front and rear main seal after a few min of looking.

Thats why I found it hard to believe my timing belt broke but then the slipping thing was brought up which chancged everything.

<small>[ October 18, 2002, 07:22 PM: Message edited by: RI-SHO ]</small>

 

[sdpatt]

The knock sensor is to protect the engine from excessive knocking. If you don't hear any knocking, don't worry too much. If you hear knocking, remove any LPM you have and try again. The knock sensor failed should not keep you below redline - unless you hear lots of knocking.

Just because you don't hear popping through the intake doesn't mean that the timing belt is properly installed. Search on checking the timing since we just went through this in great detail in this topic.

 

[RI-SHO]

Oh trust me it knocks damn loud especially when trying to hold it around idle, and it gets very lud past 4K so I stopped driving it and parked till tuesday when the part comes in from AutoZone. What is strange tho, is when I hold the gas at around 2-4K it sounds just "normal" like if I were holding when the car worked fine a few months back, so the knocking skips a certain RPM.

I remember me and my bud were like it sounds like valves tapping(we are tool ) and to think of it, it did the same thing before it was at the mechanics, only difference now it turns on all the time.

If the knock sensor does not fix the problem tuesday then I will check the timing.

One more question should I reset the EEC when I install the knock sensor? And is there anyway to change it w/o removing the manifold again?

<small>[ October 18, 2002, 10:40 PM: Message edited by: RI-SHO ]</small>

 

[SHOTIME]

Unfortunatly you will need to remove the manifold and the FI rails to get to the knock sensor.

Its a 29 or 30 mm socket to remove it. The socket to remove the spindle nut works.

Always reset the EEC when dealing with the engine. Best idea is to just unhook the battery while your working on the car and replace it when your done.

 

[BeatDaSHO]

i highly doubt its ur knock sensor. Check your timing because it still might be off.

Greg

 

[AutoSHO]

BeatDaSHO:
i highly doubt its ur knock sensor. Check your timing because it still might be off.

Greg

I disagree. If the sensor failed closed (in other words, its sending the computer a signal to retard the timing excessively) then the engine wouldn't have much power, and would also be rev limited by the fact that the ignition timing was so ********. Or, if it failed open, and the computer is pushing the timing all the way up, it would be too far advanced to rev properly. The knock sensor could very well be the culprit IMHO.

 

[sdpatt]

The engine can run just fine without the knock sensor. The EEC will use its normal ignition timing program until the knock sensor informs it that there is knocking going on. Then it will dial back the timing within a small range to try to avert the knock. The range the timing is ******** by the EEC is small enough that it couldn't prevent the knock during the hotter summer months when my Superchip was installed.

Check the camshaft timing. The engine doesn't knock at idle or when unloaded unless something is very wrong.

 

[RI-SHO]

Ok I will be doing this on this tuesday I am going to need all the electronic help I can get.

So far I have the knock sensor down because I can remove the manifold with ease, now about the timing belt cover are there any special nuts on there or can I use ""basic" hand tools to remove it? I know I can turn the crank with the crank bolt below but how will I know when I have the #1 piston at TDC w/o actually seeing it? Is there an exterior mark that is visible outside where I know the crank has the #1 piston at TDC?

Once I do that where is the timing belt tensioner and how can remove/loosen it, so I can position both cams to 12o'clock? Now if all of this goes smoothly for me, do you guys think my SHO will finally be running right or is there anything else that is being overlooked here?

 

[sdpatt]

Go here and look at what you are getting into. Use the password service.