Compression issues after startup

[spooling14b]

Hello All,

So I have a 92 tsi which I just put the refreshened (Rings/ rod bearings/ rebuilt head) 6 bolt back in. Everything went together smooth when hand cranked over in my basement there were no kinks everything was smooth and timing marks all ligned up after about 12 cranks which leads me to believe timing is good.

Cranked the motor in the car to get proper oil pressure- check

Went to fire the motor and it fired after a few cranks, revved to 3000 rpm for about 5-8 seconds then died. Tried to start the motor again and it would just crank.

There is a different sound to the motor after the intial start up, it sounds like the motor is turning over to easily (no compression).

I never heard any metal on metal like if a valve was bent and I checked the timing and it is still dead on.

The first thing that came to mind was spark and fuel. Both are working. Then I checked the compression and it is 0 on every cyclinder, not even blipping the needle on the compression gauge.

It obviously had compression at somepoint because it fired. But what happened in that 5 second period? Could a valve be open in each cylinder but not contacting the piston? I bled the lifters using the method on Vfaqs, they are 3g lifters. Could they be stuck causing valves to remain open?

When I was hand cranking the motor in my basement I did notice it would get harder then easier as the crank rotated. I used a torque wrench and for half a turn it would take about 10lbs or less to crank the motor but then it would take about 16-20 ft-lbs when the lobes were opening the valves. Could this be a sign of faulty lifters which could keep a valve open?

any input would be appreciated.

thank you.

 

[Sebba]

Timing.

What timing belt kit did you use? What rebuild kit did you use? Did you use a BSE? If so, which one?

 

[BogusSVO]

How did you align the crank marks? With the plate or the harmonic balancer and timing belt cover?

When you installed the engine, did you ever rotate it CCW?

What hyd. tensioner did you use?

 

[donniekak]

Pull the lifters out, and do a leak down test.

 

[Sebba]

Pull the lifters out, and do a leak down test.

Something tells me that won't be necessary.

 

[donniekak]

Something tells me that won't be necessary.

Pulling the rockers and lifters out will allow all the valves to close fully. If the lifters were over pumped, the valves are hanging open. If the valves are bent, the rockers will be laying all over the inside of the head when he pulls the vc. Either way, he'll find his issue.

 

[spooling14b]

Motor was rebuilt using stock oem rings, oem head gasket, arp head studs (step torqued to 90ft-lbs) , and ACL alumaglide bearings.

Balance shafts are still in the motor and both the timing belt and balance shaft belt were changed using the gates blue belt.

Head was rebuilt with new valve guide and valve seals, performed by a repuitable shop.

Stock hydraulic tensioner was used.

I timed the motor using the steps outlined in the Vfaqs. I made sure the dowl pins in the cam gears were pointed up. I aligned the two timing marks on the cam gears and clipped the belt in place. I then made sure the balance shafts were aligned correctly and that the crank was lined up with the #1 piston at tdc. I then ran the belt and tightened any slack by means of the tensioner pulley. I used the arrow on the trigger plate to align the crank I did not use the crank pulley mark.

When spinning the motor at least 12 times all the markings were in line not even a tooth off and there was no noticable kink or interference like if a valve was hitting. The only thing that was noticable was that at some point in the cycle it would get a little tougher to spin the motor like with the cam was fully opening a valve.

But like I said the motor did fire for a few seconds but after it would just turn with no ignition not even a puff.

 

[BogusSVO]

The shop that rebuilt the head, just how familiar are they with the 4g head?

The 4g head is a tad tricky if you do not know how to set them up.

With the new guides, they had to cut the seats, that will raise the valve tip height

Now if you went with used stock valves that were ground, that will raise the tip height even more.

So if they did not check and set tip height, when the HLA's pump up into place, they will crack the valves off the seat, and you will have low to zero compression.

 

[spooling14b]

I had them do previous heads for me in the past. When i went there to get this head rebuilt I asked how familiar they were with the 4g63 and they pointed out 4 other heads they had already rebuilt that were ready for pickup and they said that they did them all the time.

Previous jobs came out very nicely including my previous vr6 head which they had never done before.

But obviously there is always human error so I can't really rule ouot mismeasuring.

 

[Sebba]

Pulling the rockers and lifters out will allow all the valves to close fully. If the lifters were over pumped, the valves are hanging open. If the valves are bent, the rockers will be laying all over the inside of the head when he pulls the vc. Either way, he'll find his issue.

I wasn't disagreeing with you, you and Bogus are probably spot on.

 

[spooling14b]

So if the issue is the lifters, is there a way to remove them without removing the timing belt?

 

[boost97gst]

Bogus taught me this: I believe you can. Remove the followers or rocker arms. You can use a long heavy duty flatblade screwdriver to get this done. At that point(and im not looking at my valvetrain right now) i THINK you have room to just pull the HLAs out. Thats not going to fix valve height though.

Rotate to tdc on compression stroke on one cylinder and try a leakdown. If you hear air coming from intake and exhaust or one of them then you know for sure its a valve issue.
Use a long screwdriver to make sure you are at tdc and watch the lobes so youre sure youre on comp stroke. Simple right?

Good luck bro, my low compression was NOT the valves and im still stressed and bummed aboutit. You on the other hand might have a very good chance of a simple valve problem.

 

[gsx4g64]

Did anyone ever find out what the problem was? I'm having the same exact issue right now. I have zero compression across the broad. Everything inside the motor is brand new. Was it the lifters? Mine are pumped up.