cold start, no decompression yanmar1500

[CoyPatton]

A pressure leak down test checks the integrity of the cylinder. You want to rotate the engine until both valves are in a closed position. Then you charge the cylinder with air pressure with a gauge in the line. You remove the air supply with the line closed so that pressure is maintained to the cylinder. If it loses pressure, you check for where air is escaping. You will possibly have to reattach air supply.
This way you can determine what is at fault in the cylinder—valves, rings, head gaskets by where you find your air loss escape path.
If the valves are out of adjustment, you will not find that with a radiator leak test ever. Nor will you know if the rings are bad.
Bottom line, I would hate to do put a head gasket on only if the engine needs to be rebuilt!

 

[careyo63]

COMPRESSION TESTER KIT -: Yanmar Tractor Parts

 

[CoyPatton]

Nothing wrong with a compression tester. And it provides useful information. But it is not a leak down tester.
Of course if you have compression within specs, you do not need to do a leak down test.

 

[ziggywiggy]

Ugh, well I may have found the problem...I checked the oil and it was low. I'm kicking myself because I don't know why that wasn't the first thing I checked, I guess because I didn't see how that could lead to power loss? I topped it up and am praying I caught it time, but now that I've added oil the white smoke is coming out of the main exhaust not the crank case exhaust? I'm not really sure what else I could look at to see if it's ok, I ran it for several minutes and it gave no sign of shutting off, just white smoke. When I checked the radiator there were no bubbles but the water is rusty colored, the oil that I did see was black and not milky. I don't know, I'm planning to test drive it tomorrow and see if it still functions.

Edit: by main exhaust I mean muffler, smoke was originally coming out of the crankcase and now it is coming out of the muffler instead

 

[careyo63]

If you end up with low oil or already have it lower. Then you can almost guarantee you have bad rings. So run it see what happens. It clears up or oil use and smoke still. Then you are pulling it down. Don't run out of oil and take out a main bearing also. And you don't want to damage the Piston and Cylinder anymore than it already has.

 

[rScotty]

Nothing wrong with a compression tester. And it provides useful information. But it is not a leak down tester.
Of course if you have compression within specs, you do not need to do a leak down test.

Sometimes there will be very small leaks in the head gasket that do not show up well in a leakdown test because of the normal leakage past the rings.
It's not unusual for the first sign of head gasket going wrong is for it to be seeping a few drops of antifreeze into the cylinder overnight. You'll see that in the smoke when starting from cold, but it may be years before it gets to be a large enough leak to show on a test.

It's hard enough to see these early tiny leak paths when the head is off, the gasket is hanging on the wall, and you are going over the surface of the head and block with a strong light and magnifying glass. But they are there.... or not....

Another problem with any type of head gasket test is that head gasket leaks are usually temperature sensitive. So you have to expect that they will leak differently with the engine warm or cold.

Of course all this about what test to do is just so much nit-picking if the head gasket has gotten to the point that the white smoke is coming out the exhaust when the engine is warmed up and working. That means that the poor old diesel engine is pushing out water vapor with the exhaust and it is time - or past time - to do a head gasket job. That gasket actually one of the easier and inexpensive jobs to do on a diesel if you get to it before the leak etches too deep a path in the head. Anyway, It's usually worth taking the head to a machine shop to have it flatted and maybe inspect to see if it is also time to do a valve job while it's convenient.

Luck, rScotty

 

[careyo63]

When you do have a small leak pumping up the radiator with back pressure it's real hard to find exactly what the problem is. Sometimes it may take more time for it to over pressure the Radiator. How long you use it. How hot it is outside. How much water is In the Radiator. Etc. Etc. So many different things that cause it to happen. That's where this comes into play and a very good tool to see what's happening.
https://www.tooltopia.com/_img/STN/STN12270.jpg
Say you start it up and in a matter of a few minutes your up to 15-16PSI. you can pretty well take it to the Bank you Have a Head Problem. I don't mess around trying to diagnose a Head once I know there's a problem. Then I just take the Head to a machine shop and let them go through it. Which for me is my local NAPA store. It has a machine shop in the same building...

 

[clemsonfor]

You will loose power cause of low oil cause you may be seizing on the crank or in the cylinder due to lack of oil? I am not sure this is your problem. Especially if you were only low a quart or qt and a half or something. White smoke is unburned fuel also. Is there a chance your rings are so bad that unburned fuel is blowing by down into the crank case and out the vent on startup? I would be surprised it would have compression to start if that was the case. White smoke out exhaust that cleans up or darkens upon start up would not really be cause for concern especially on an engine with some wear on it. Worn engine may explain where your oil went.

And those lines I think your talking about , is that the ones that goes from injector to injector then back to fuel tank? If so those are not bled lines, they just send extra fuel back to the tank. There just replaced , you don't bleed them. Now if your talking about the rubber line from tank to filter or filter to pump, those do have to be bled, at filter, then at pump to get all air out. But this should be very easy and done in about 30 seconds.

 

[Jtullis13]

How long have you had this tractor? Is it a recent purchase, had it been sitting for some time prior to this? Sorry I didn't see if you had posted this somewhere.