Need help after foolish mistake

[Marc87GN]

I have only had my 87 GN for a week and I blew something in the engine last night. When I bought the car, I found that the TPS was set at .51, fuel pressure at 54 psi and one of the coils had high resistance and then went open.

I set the TPS to .42, fuel pressure to 42-44 psi and ordered a new coil pack, wires, plugs & heated o2. The car was only making about 15-17 psi before. I installed all of these parts last night and the car ran well. I went out for a drive and I saw that the turbo was making 15 psi+ on the cluster at 1/2 throttle. The car also has a pillar mounted boost gauge, but was not lit for me to see it. I was on my way back home and was getting on the expressway at about 1/2 throttle and turned on the interior light and saw the gauge pegged at 20 psi. I let off of the throttle and heard a loud boom. Needless to say, I was towed home at midnight.

After the tongue lashing I took from my wife, I put it back in the garage. It just turns over, but will not fire. There are no leaks anywhere so I suspect I broke the timing chain. I plan to pull a valve cover and see if the rocker arms move up/down. I hope I didn't damage the engine though. Any ideas are welcomed at this time.

 

[Slow91z]

Is there milk in the oil??? Cuz it sounds like a head gasket...If there's milk in the oil DO NOT START IT.

 

[Marc87GN]

The car will not start at all. I haven't had a chance to take a good look at it yet since I got home at Midnight, but I didn't think a head gasket would keep it from starting. This is why I suspect the timing chain.

 

[Slow91z]

The head gasket is usually the first thing to pop due to overboosting, and yes it could keep it from starting.

 

[Marc87GN]

Can you recommend a place and type to get new head gaskets?

 

[Slow91z]

Do a search there's LOTS of info on this subject here already...But as for my opinion most cars do just fine with the stock ones, they act as a "fuse", so to speak, blowing before you do damage to the rotating assembly...if you are going all out and want to push it to the limits then Comectics are supposed to work well...You can get either from most Buick vendors I would think.

 

[MeanBuicks]

Originally posted by Slow91z
and yes it could keep it from starting.

How is that? I've been around numerous TRs with popped gaskets and they've always run, albeit rough.

 

[TR Custom Parts]

Maybe an intercooler hose popped off?? Not sure if it would still run with it off or not?

Would think the only way a head gasket would not allow the car to start would be if it was leaking coolant into the cylinder so bad it hydro locked? His car is turning over so it isn't that.

 

[Slow91z]

I've seen HG so bad they won't run, no compression and messed up plugs will do that...If it was a intercooler hose then it would start and die, at least mine did.

 

[kh440]

Easiest way to eliminate the timing chain: unscrew the cap off of the cam sensor, spin the engine over and see if the sensor ring rotates (much like a rotor button) If the chain is broken it will not rotate. Also, does it spin over faster than before or about the same speed?

 

[Marc87GN]

Originally posted by kh440
Easiest way to eliminate the timing chain: unscrew the cap off of the cam sensor, spin the engine over and see if the sensor ring rotates (much like a rotor button) If the chain is broken it will not rotate. Also, does it spin over faster than before or about the same speed?

We are on almost the same page. I pulled the oil fill neck and had my wife crank the engine. the rocker moved up and down just fine so I probably blew a head gasket. The weird thing is, the coolant looks fine and the oil looks normal. I'm going to pull of the plugs and do a compression check in a little while. It was such a loud pop that something significant let loose.

 

[Slow91z]

Hmmm that's kinda strange...I would figure a HG bad enough to keep it from starting would create a HUGE milkshake...Keep us updated this sounds interesting.

 

[Jay Wicks]

Check the cam sensor, it sounds like the roll pin sheared at the base gear or the interruptor wheel broke. It is located at the front of the intake where the dist would be on a normally aspirated motor. Jason Cramer has a repair kit available for this.

 

[scottyb]

check crank sensor, too.

 

[Marc87GN]

Thanks for the help guys and I will check them next.

I just ran a compression test on all cylinders. Throttle open, ECM disconnected and all plugs out and these are the numbers.

Cyl# 1 160 psi
Cyl #2 161 psi
Cyl #3 158 psi
Cyl #4 161 psi
Cyl #5 161 psi
Cyl #6 168 psi

I'm certain the head gasket is fine at this point. The cylinders also held pressure for a few minutes and barely leaked down at all. A 50K engine should be this tight. The engine appears to be fine. I will check the Cam & Crank Sensor now. Fuel pressure was fine. The coil pack, wires & plugs are a day old so they should be fine. I will be back.

 

[gokada]

Originally posted by BuickGn Boosted
Maybe an intercooler hose popped off?? Not sure if it would still run with it off or not?

Ditto......Especially if you heard a loud pop.

 

[Marc87GN]

I have actually had the up pipe from the intercooler to the throttle body off and the engine would idle fine. I was cleaning the the throttle plate & Iac bore. I checked the hoses and everything is tight. The guys may be on to something with the cam & crank sensor.

 

[Slow91z]

Dodged a bullet there...I'm glad it's not a HG, the stock seal is the best seal.

Do you have a scan tool?? If it ran fine with the up pipe off I would say the cam/crank sensors are ok, maybe a mass air problem?? I only ask cuz Mine always dies if I start it with the mass air not connected.

Pops under boost sometimes suggest coil pack/ign. module problems.

 

[Jay Wicks]

Seen this many, many times. After your on the throttle and then come off, the top shears the interruptor on the cam sensor and you hear a loud POP! Check the cam sensor, if its ok on top, , roll the motor to be sure it's turning and you didn't shear the rollpin.

 

[NEARING]

Originally posted by Jay Wicks
Seen this many, many times. After your on the throttle and then come off, the top shears the interruptor on the cam sensor and you hear a loud POP! Check the cam sensor, if its ok on top, , roll the motor to be sure it's turning and you didn't shear the rollpin.

That happened to me once too.