Can't find leak with UV Dye

My 1981 bus has an R22 leak. UV dye leak detector has been applied to pin point the leak. Since it all leaked out in about 4 months time, I assumed it was a large hole and was looking for a big smudge in the high presure side. But I have only found very small specs of the dye all around the unit. Some at the hose connectors, expansion valve, on the condensor. Just exactly what am I looking for? Or have I already found already it?

The system is powered by a Thermo King x426. SHould I remove the clutch and look at the shaft?

Any insight from the proffesionals would be welcome. I have taken my bus to about 12 shops and when I mention R22 they all scurry.:mad: So, I'm here.:)

You seem to have found what you are looking for.

The size of the trace is no indication of the volume of the leak.

Traces of dye on the outside indicate a leak, especially in those areas you mentioned. Shaft seals are also prone to leakage, particularly during long periods of inactivity.
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Ferrari F1 640

Hi jd,

As Argus has said have already of found your problem.

But...... speaking from experience UV dye does not always show the leak up.

Sometimes leaks on the low pressure side do not show up with the dye and the only way it be sure is to pressure test with OFN.

The leaks that the dye has shown up may only be fractions of an oz. a year, leaks that should be rectified all the same, but not the cause of your problem.

The only area that OFN tends not to work is that of the compressor shaft seal.

I would suggest you pull the clutch off and test round the shaft seal with a leak tester. If you get a reading replace the seal but check the compressor main bearings first. If the bearings sound noisy you will need a rebuild otherwise the new seal will fail in double quick time.

Hi, I'm very unfamiliar with bus cooling and the lay out, but from the description, I think I'd be inclined to concentrate on the tev joint and hose connectors and definatly have the pulley/clutch off the compressor for shaft seal inspection. Where abouts is the dye on the condenser?

I'm not too much of a fan of uv dye although it does have it's good points, or does it? the thing I hate with these dye's is that when some escapes it sometimes catches the air flow of say the evap fan or condenser fan and even the air movement when the vehicle is moving and I find the dye gets splattered everywhere usually making things look worse than they are.

Give me ofn and soapey water any day.

Has anyone had any problems with some dyes seperating and balling up?

Some of the ads for the dyes show a lot of dye leaking out thats usually not the case. The dye is circulated through the system with the oil, so the minute amount of oil that escapes in some areas with a leak will only show up as a small trace. Only on the compressor where you have a large amount of oil being able to leak out will you have a trace of a large leak.

If you have no evidence of major leaks anywhere else in the sys then I suggest you change out the shaft seal and have a look at the state of the crank running seal surface as well.

If your doing the shaft seal, always check the end play of the crank. If the crank is walking, this could cause the shaft seal to leak premature and sometimes intermitantly! Just as ReeferJon said, check the sealing surface on the crank as well, it most likely has cast crank. If it is forged, it will have a small ring cut at the nose of the crank. Good luckj