Stumped!

[PGHMAN]

To do a leak test... you have to bolt on covers over the manifolds. Did you do that?

Yep, the exhaust and intake manifolds are blocked. The odd thing is when I remove the hose blocking the elbow on the exhaust manifold it's retaining pressure but it's not getting back to the gauge that's connected to the cylinder head cover.
As we know the top end test routes through the cylinder cover/head into the cylinder wall jacket to the exhaust manifold. That's where I am stumped on why I can have pressure on the low end of the manifold and not back on top.
I'll post some pics later.....losing sleep on this one.

 

[Dr Honda]

hum....


some pressure should get past the rings and register in the upper. Try rolling the engine into a different spot.

 

[68ragtop]

Are we talking about the water jackets? The top head is independent of everything else on the 720 I believe.
I was reading the posts & am confused if your testing the cooling side or the fuel (internal case) side.

As far as the earlier post, I was saying it looked really rich, but that really depends on how your running it. IMO you don't need to baby the heck out of a new engine. The only thing your trying to avoid during break in is too much ring pressure against the "rough" crosshatch of the fresh cylinders. The harder you run it at WOT the more pressure in the combustion chamber & the more friction on the rings/cylinder walls. But, you need some & its actually important to do a few WOT bursts to keep the rings seating as the cylinders start to wear.

Kinda getting off track here & that thought has nothing to do with your issues, but I think your lack of build up on the pistons is from lack of harder, higher temperature operation. Its like trying to read the temperature of fresh spark plugs a few minutes after install. they won't show much of anything.

I think you are testing the water jackets for possible leaks into the case, & the case for leaks into the atmosphere?

 

[jimmaki]

Yep, the exhaust and intake manifolds are blocked. The odd thing is when I remove the hose blocking the elbow on the exhaust manifold it's retaining pressure but it's not getting back to the gauge that's connected to the cylinder head cover.
As we know the top end test routes through the cylinder cover/head into the cylinder wall jacket to the exhaust manifold. That's where I am stumped on why I can have pressure on the low end of the manifold and not back on top.
I'll post some pics later.....losing sleep on this one.

Can you describe your test setup? Are you testing the engine crankcase leak down or the cooling system? How exactly did you block the exhaust and intake manifolds? Are you using the parts normally bolted on there with gasket or rubber material in between?

 

[PGHMAN]

I am testing the both the top and lower end. I have block off plates on the intake and exhaust manifold plus have pinched the various hoses. I tested the rotary cavity and discovered a leak on the front seal. I replaced the inner and outer seals when I originally rebuilt but discovered earlier today when I pulled the shaft there was a small amount of corrosion on shaft where the front seal rode. Polished the shaft and replaced the seal with a new one - tested fine. Tested the inner crank seals by removing each plug and no issues there.
I know the post is somewhat confusing trying to describe the leak test but I'll post some pics of my set up later today and attempt to better explain.
Thanks guys.

 

[PGHMAN]

Spent the day attempting to leak test the top end/cooling system but continue not to no have reading on the gauge but when I pull the cylinder cover hoses as well as the lower drain hose on the exhaust manifold there's pressure within. Stumped but will post pics of the setup shortly.

 

[jimmaki]

You may have stated this earlier in the thread and I missed it, but can I ask what problem you're trying to solve by pressure testing your cooling system? Where are you attaching the gauge and is the source of pressurized air at the same point as the gauge and if not where? Reference the fitting numbers, 4,6,8,9,10 or the head cooler 11 and which one(s)?

 

[PGHMAN]

Sorry guys, decided to step away from the engine yesterday to clear my head. During the pressure testing of the cooling system I have the cylinder cover inlet and outlet ports (11) looped, the elbow on the exhaust manifold (9) plugged, and am pressurizing through the outlet port on the cylinder cover on the mag side. The motor retains pressure......I can remove any of the plugged/looped hoses and hear sufficient pressure being released even after multiple minutes. The odd part that I am not getting a reading on the gauge. I know it sounds crazy but I have used the gauge to pressure test my carbs, etc. with no issues receiving a reading on the gauge.
The gauge setup is simple, schrader valve, gauge and barbed fitting on a T. I'll post some pics later when I get home from work.

 

[jimmaki]

Can't see how anything the engine would do to make the gauge not read if I understand the setup from your description. Maybe test the gauge off the engine by blocking the t-fitting normally going to the engine and see if you can get it to read by pressurizing the schrader? Maybe none of my business, but I still don't get why you're pressure testing the cooling system. Is the engine ingesting water?

 

[PGHMAN]

That's a thought....I could attach the gauge to the manifold elbow to possibly obtain a reading. I just want to verify no leaks before I reinstall the motor. I did have leak on the outer rotary shaft that I replaced on Saturday. The mag side of the lower end case had about table spoon of oil in in. Earlier in the post I showed a pic of new plugs and the mag side plug was covered with oil.

 

[jimmaki]

Hmm, ok, but if compression is good the only other cooling system leak I can think of would probably show up at a pipe manifold gasket or plug weldment no?

If just the mag side of the case had oil in it, I'd probably suspect the mag rv inner crankshaft seal. I sure you pressure tested the rv cavity after replacing the rv shaft seal. Odd it just dumped oil in the mag side.

 

[PGHMAN]

Had no leaks on the pipe when it was installed and rechecked the passages over the weekend.
I tested the RV cavity after I replaced the outer seal and held 5psi indefinitely. Also, pulled plugs to confirm inner seals and again held indefinitely.
I maybe thinking too much into this but want to be certain the engine is sound before I reinstall. It does seem to run much hotter than my 787 GTX. On the GTX the cylinders are warm after a run but this ski the cylinders are hot and I am barely able to keep my hand on the cylinder for a second or two.

 

[jimmaki]

Might be more of a blockage than a leak. Have you felt the temp of the outgoing coolant or the hoses and compared it to the GTX?

 

[PGHMAN]

I've gone through the cooling system to include the various hoses (most are new), cylinder head/cover, pipe and cylinders and all clear. I can see the water flow out the clear hose to pee hole. I have not felt the water out the pee hole but could next time I am out.
I did swap the 140mm jet pump during the rebuild and thoroughly cleaned and inspected each hole/passage for debris before installing.

 

[jimmaki]

I think the cylinder jacket water is preheated by the pipe, I don't think it comes from the head. Could be why you're not seeing anything on the gauge. Might be a different path than the GTX, so, maybe the difference in temps?

 

[PGHMAN]

I'll have to research the flow on the GTX. You're right on the flow on XP through the head into the pipe then into the cylinder jackets. Thanks for taking the time to help . Getting rain from the front that's in the gulf?

 

[jimmaki]

No prob ... could tell you were getting frustrated, glad to help. Yeah, it's been raining off an on the past two days.

 

[PGHMAN]

Ok, I'm an idiot! Spent the past two evenings retesting the engine for leaks and discovered after using my air compressor with regulator at 5psi and a gauge on the an outlet that I never applied enough pressure to ever register and reach 5psi on the gauge attached to the outlet.
I was always concerned to avoid blowing a seal.....a lesson learned.
Tested both the top (coolant) and lower end and each held for over 10 minutes without zero drop. Tested 3 time to confirm.
. I am hoping the leak I discovered over the weekend on the rotary shaft may have contributed to the rich mixture causing the difficult running. I've gotten good at pulling the motor and installing . [MENTION=16022]Dr Honda[/MENTION] I may still take you up on sending the carbs to inspect but would like to test this weekend before sending.
Very sorry for the trouble but I am very truly grateful for those who gave guidance and support during my post.

 

[jammin777]

hope all is well so that you can got on with some fun.

 

[jimmaki]

Glad you found the problem. Those air compressor regulator gauges can be off, especially at very low settings. I usually use a bicycle pump for low pressure tests, but not because I don't have a compressor.

I'm probably wrong but it looks like pressure comes in the exhaust ports and the meter is on the pulse port? Probably not the cooling system test setup?

 

[PGHMAN]

hope all is well so that you can got on with some fun.

Hi Kevin - hasn't been too bad since I had the GTX to get out on. How are things with the new ski? Some day I will buy a newer one...once I get the kids out of college .

 

[PGHMAN]

Glad you found the problem. Those air compressor regulator gauges can be off, especially at very low settings. I usually use a bicycle pump for low pressure tests, but not because I don't have a compressor.

I'm probably wrong but it looks like pressure comes in the exhaust ports and the meter is on the pulse port? Probably not the cooling system test setup?

Jim - I was careful on the initial check using the air compressor and regulator.....I was worried about the inaccuracy of the regulator at a low setting as well. Once I saw a reading on the gauge connected to the pulse line I then switched to my bike pump.
For the cooling test, I looped the two rear ports on the cylinder cover, blocked the exhaust manifold, placed gauge on exhaust drain hose and feed through the front port on the head cover.
As noted it became frustrating not being able to acquire a reading but I obviously under estimated the volume to fill the engine cavity. Rookie mistake

 

[jammin777]

I'm glad that you have another ski to cool off the summer heat with,
I absolutely love my new ski, has been running great! went out last friday and will again this friday. only has just under 4 hrs on it so it is not broke in yet.