leak down/ pressure test results on newly rebuilt 717/720

[abadaba]

Im in the process of rebuilding a 2005 GTI. The pistons and cylinders got "pittied" (massively)for reasons unknown. I pulled the cylinders and sent them and the pistons along with the spark plugs, to Full Bore and got the WSM Platnuim deal with the cylinders resleeved. They advertise that if you send the cylinders, pistons and spark plugs, they will tell you what caused the problem. Needless to say, they didnt tell me what caused the problem and when I send them an email inquiry, they dont respond. Thats kinda beside the point of the post but maybe not. Im putting the motor back together, I have the intake and the exhaust blocked off with a gauge on the exhaust side. When I pressure up the cooling system to 5 psi for 10 minutes, Im losing about .2-.3psi in 10 minutes, but the gauge on the exhaust block off plate comes up. This leads me to belive that I have a minor leak between my cooling system and the lower end. Ive taken the cylinders off several times, rolled a thin layer of yamabond 4 on both sides of the lower cylinder gasket and put it together. Ive replaced the rubber gaskets on the top of the cylinders, twice. Still get the same results.
My question is, is this much of a leak something that i need to worry about? Having spent the money for the pistons and cylinders as well as buying a new crankshaft, I really dont want to have the same problem that caused this whole mess in the first place.

 

[DanSquires]

Im in the process of rebuilding a 2005 GTI. The pistons and cylinders got "pittied" (massively)for reasons unknown. I pulled the cylinders and sent them and the pistons along with the spark plugs, to Full Bore and got the WSM Platnuim deal with the cylinders resleeved. They advertise that if you send the cylinders, pistons and spark plugs, they will tell you what caused the problem. Needless to say, they didnt tell me what caused the problem and when I send them an email inquiry, they dont respond. Thats kinda beside the point of the post but maybe not. Im putting the motor back together, I have the intake and the exhaust blocked off with a gauge on the exhaust side. When I pressure up the cooling system to 5 psi for 10 minutes, Im losing about .2-.3psi in 10 minutes, but the gauge on the exhaust block off plate comes up. This leads me to belive that I have a minor leak between my cooling system and the lower end. Ive taken the cylinders off several times, rolled a thin layer of yamabond 4 on both sides of the lower cylinder gasket and put it together. Ive replaced the rubber gaskets on the top of the cylinders, twice. Still get the same results.
My question is, is this much of a leak something that i need to worry about? Having spent the money for the pistons and cylinders as well as buying a new crankshaft, I really dont want to have the same problem that caused this whole mess in the first place.

Usually Fullbore will give a description of the failure on the receipt sent with the top end.. do you still have that?
When did you email them? I would say if they don't respond within a day or two during the work week, give them a shout.

I want to be clear on what I think I'm reading.. you're getting an air leak when you're pressure testing the cooling system, and you believe the air is leaking into the cylinders.. correct?
What does your pressure testing setup look like?
I doubt its between the cylinders and cases, especially if you've used both a gasket and sealant, unless the gasket has been compromised.

When I pressure test a build, I'll do the RV @ 8 psi for 1/2 an hour, cooling system @ 8psi for 1/2 hour, and then the engine itself 8 psi.. that usually lasts overnight since I just walk away from it until the next day, and I do not have any pressure loss in any of these three tests.

 

[abadaba]

I finally did hear back from fullbore but unfortunately, I don't have the receipt, I didn't even look at the receipt, my bad, I assumed that they would have left something inside with the parts. As for my set up, I've got a plate with a 1/4" threaded port on the exhaust manifold, theres a ball valve w/ 0-15 psi gauge screwed into the port. I have a plate on the intake manifold that has a 1/4" threaded port thats got a ball valve w/ 1/4"- barb fitting screwed into the port. When I pressure up the cooling system and let it sit, the pressure will rise on the exhaust manifold gauge. when I pressure test the lower end alone, the pressure will drop to zero over the course of several hours. When pressured up, I can spray soapy water all over the engine, not seeing any bubbles

 

[DanSquires]

At .3 PSI (3/10 OF A POUND) over 10 minutes, I would say you're fine.
Did you put any sealant on the rubber o rings on the head? Did you torque down the manifold before torquing down the cylinders?

If you're super particular, you could try first removing the manifold and blocking off at the cylinders instead, and see if you still have a drop in pressure. If your results are the same, then it's in the cylinders.
If the drop goes way, it's in the manifold.

 

[abadaba]

I did put locktite 518 in the oring grooves and at one point I did put sealant on the top of the orings before I put the cylinder cover back on, I did torque the exhaust manifold before I torqued the cylinders. I will think about removing the exhaust manifold and making plates to block the cylinders, are you thinking I may have a leak within the manifold?

 

[DanSquires]

possibly.. or at one of those gasket points. Again, at .3psi/10 minutes, I wouldn't go off the deep end searching..

 

[abadaba]

So you dont think that I may get water leak into the cylinders? What originally brought me to this point, I bought the ski, took it out the first time, no issue, the second time, after riding most of the day the ski bogged down and wouldnt get back up to speed. When I had it home, I pulled the spark plugs and one of the electrodes was closed, no gap at all. I put in fresh plugs and the next time I went out I rode most of the day before she bogged down agin, got her home, pulled the plugs and the oppisite plug as before, had no gap. Again, put in new plugs, changed out my oil (I thought it might have been contaminated), took her out again and same issue. At this point I pulled the head cover this is what I found. I may have gotten water in my fuel as I found that my fuel cap had a small crack in it but honestly I dont know where the water was coming from, if infact that is what cause the problem. I would love to not go off the deep end or at least any deeper then Ive already gone.

 

[mikidymac]

Follow the manual. The exhaust manifold should only be finger tight when tightening the cylinders. Also you want the cylinders as close as they will go in the middle so they are almost touching each other. For the base gasket only a very very thin smear of 1211 or dry. No Yamabond.

The standard for engine leak down is 8 psi for 10 minuets. After that don’t worry about it. I don’t check the cooling system other than to see if it immediately holds a couple pounds. All you are looking for on that is a crack or missing gasket.

The engine leak down is the important one. Also check your gauge setup for leaks.

 

[abadaba]

1211 is impossible to find in my area but the yamabond, which is a fourbond sealent, was applied as suggested in the manual for the case halves, with a roller.The manual calls for 34 kPa or 5 psi for 3 minutes for the lower end, in 3 minutes time I'm not gonna see any noticeable pressure drop. I guess that goes for the cooling system too as I just read the manual again and it states 3 minutes for the cooling system also. Would that mean that Im good? Ive read so many posters saying that they pressure up and come back the next day and the pressure is holding, I was able to do that with the rotary valve chamber but thats about it.

 

[mikidymac]

The Yamabond is for metal to metal and a thicker sealant. 1211 is more of what you want on gaskets.

As for the time 8 psi for 10 minutes is the rule of thumb.

 

[abadaba]

8 psi for 10 minutes, after which it should still be at 8 psi or is there an acceptable amount of pressure loss?