Another cooling problem?

[douglee25]

OK, here are the details....

Symptom: I rode today for about 4 hours. Everything was fine until last 10 mins I noticed that pisser #2 (rear cylinder) was not flowing much at all.

Cooling setup: Pump to bottom of exhaust manifold (single cooling), front nipple on head to pisser #1, rear nipple on head to top of head pipe (riva red pipe), bottom of head pipe to T where one line goes to pisser #2 and the other line goes to a jetworks valve on the stinger.

Tests:

1. Compression is 180 rear cylinder, 170 front cylinder.
2. Running the ski on the hose does exactly the same thing as it does in the water.
3. Back flushed every hose. Flow is great out of all hoses.
4. When running on the hose, pulled line from front of head going to pisser #1. Flow is outstanding. When the line is hooked back up, pisser also shows outstanding flow.
5. When running on the hose, pulled line from back of head going to top of head pipe. Flow is not even close to that of the front of the head. Hooking the line back up exhibits the low flow seen on pisser #2.
6. Pulled nipple off of rear head. Nipple is clear.
7. Hooked hose up to rear of cylinder and flushed to front. Good flow out the front nipple.
8. Hooked hose up to front of cylinder and flushed to back. Good flow out the back nipple.
9. Ran ski on hose and pulled both lines from head off simultaneously. Front has great flow but rear is still low.
10. Front piston (170 psi) has a good carbon pattern. Rear piston (180 psi) has little to no carbon on piston crown.

At this point I'm stumped. I thought it could be a blown O-ring on the head (protec). I also brought piston to TDC on each cylinder and flowed water into the head. No water was seen in either hole. I even bumped the starter and nothing came out.

It's obvious that there is not an obstruction in the raw water line from the pump if the front portion of the head has great flow. It can't be a line after the head pipe because the low flow seems to be coming from the back of the head. Could there be some sort of obstruction in the cooling passages inside the jug? How about at the entrance to the jug where the exhaust manifold bolts up? Head O-ring?

I'm stumped?

Any suggestions?

Doug

 

[sflsurfrider]

single cooling and 2 pissers? bad idea unless they are restricted.

can you blow back through pisser #2 into the head without obstruction?

 

[douglee25]

single cooling and 2 pissers? bad idea unless they are restricted.

can you blow back through pisser #2 into the head without obstruction?

Pisser #2 is restricted right at the inlet into the pisser in order to get the jetworks valve to open correctly (at the right rpm that is).

Back flow through pisser #2 is not a problem. Like I said though, if I disconnect the line coming from the back of the head, flow is low. Right there that bypasses pisser #2 and takes it out of the equation.

Why would that be?

Doug

 

[sflsurfrider]

but can you take that line you took off of the head and blow out toward the pisser?

 

[douglee25]

but can you take that line you took off of the head and blow out toward the pisser?

Yes, no obstructions. If I pinch the front line coming off the head, flow does increase on the back (which it should). Even when I do this though, flow is not substantially increased through the pisser, just the nipple on the back of the head. I'm pretty sure the jetworks valve is opening at that point.

Doug

 

[douglee25]

I blocked both cooling outlets on the head and hooked up the hose to the bottom of the manifold. I still did not see any water in the cylinders after pressurizing them. I even bumped the starter several times, and still I didn't see anything squirt out. I decided to pull the head regardless and check the O-rings (gotta love pulling the Riva red pipe - PIA). I didn't see anything unusual, but I will purchase new O-rings anyway. I pulled both nipples on the head. They are clear with no obstructions. I've pulled every hose and they are all clear. The only thing I didn't check yet is the inlet tube from the pump and the T fitting at the flush hose (raw water inlet goes through T fitting). If I hooked the hose directly to the manifold line, I got even discharge from the two head outlets. As soon as I hook it up to the flush adapter, I get one nipple with great flow, and one with low flow. I'm assuming this is because a portion of the water exits through the pump.

Any suggestions besides checking the T fitting and the inlet tube?

Doug

 

[douglee25]

Today after work I pulled ride plate and pulled the hose off the pump. I was able to run weedwhacker string all the way down the thru hull pipe without issue. I then bent it slightly for a 90 degree angle and it went through the pump fitting without issue. No clog there. I pulled every T fitting throughout the cooling system and every nipple fitting on the head and pipe and still there were no clogs. I'm lost. I suppose it's still possible that one of the O-rings leaked while it was running but would not leak with just hose pressure on it. As I said before, one piston was def. cleaner looking than the other. The other possibility could be indeed there was something stuck in the line and when I backflushed it, it may have come out without me seeing it.

Nevertheless, I've ordered new Viton O-rings from Mcmaster. I'll throw the engine back together and see what happens.

P.S. While the engine was all apart, I cleaned the engine bay with simple green and a brush. Boy does it look puurrrrdy now! :Banane01:

Doug