Leak Down Test---Is this Right ?
 

My mechanic did a leak down test on my 3.5, 03.

The car blows white smoke on cold start up, but then runs with no smoke. Lately, car has been over-heating and i have to add coolant every few days---uses about 1 qt of coolant. HOWEVER, the car runs strong, no loss of power. I have been getting multiple misfire code of 0300.

SO...I had a leak down test done and the Mechanic said all 3 front cylinders are leaking at 20% (or therebout). To me that sounds like a lot of water loss. When the mechanic did the leak down test, he did not pull the radiator cap. Since he had the Intake Manifold off, he had one of the cooling system hoses already disconnected and when he saw water, that's when he got his measurement and indications of 2, 4, 6 cylinders. He said the HG was shot in the Front Head. The car only has 96k.

1. I thought that leak down test were done with a un-capped Radiator, and pushing air into the cylinders and waiting to see which cylinder gave off Air?
2. Is it possible that Leak down was done wrong?
3. How can the Car run that strong..and be leaking from 3 cylinders ?

---Not looking good here :(



.

I'm guessing you don't see any coolant on the ground. Did the mechanic do a cooling system pressure check? The way you describe what the mechanic did does not sound right.

White smoke is not necessarily water, it can also be oil in a small amount. Cracked compression rings and valve guides do this. To tell what the smoke is, sniff the exhaust cloud. If the white smoke is engine coolant, it will smell sweet. Oil smells a lot different.

If the head gasket is leaking coolant, the coolant can go 3 places - in a cylinder, an oil passage (and end up in the oil pan) or leak out on the ground.

Thanks Dennis,...

After i got home from Mechanic, I did a pressure for 30 mins----and saw a small drop of coolant on the ground near the front area, near the water pump. Nothing significant. a drop or two. YES, the exhaust smells of a sweet funky incent smell---. However, I took a look at the dipstick and there is no water or dis-coloration?

FACTS
-white smoke with sweet smell
-losing or burning coolant (have to 1qt every 100miles or so)
-leak down test, mechanic says front 3 cyl are leaking
-the car does misfire, (but not too bad) BUT getting 0300 code

QUESTION(s)
-Is it possible to have HG leak from 3 cylinders and no Oil discoloration?
-If HG is leaking from "FRONT 3 cylinders", why am i not losing power?


Ugh---:(

You may find this video helpful. I subscribe to this guy on youtube. He has a lot of great information on autos from diagnostics, repair, understanding how components work, etc.

Thanks Manry...(i could use all the help i can get at this point)

ehh...what video ?


?

It is embedded, do you have flash player? If not, follow the link below.

https://www.youtube.com/watch?v=WgrfT0LFMhc

usually the white smoke I have smelled before didn't smell sweet, but smelled weird and pretty pungent. it's an indication of a blown head gasket, and hopefully in your case, it's just the gasket, I have heard worse such as cracked head. good luck on solving the problem. Generally Head gasket on the VQ engine are pretty good, but only way you can blow a head is driving the car overheated and continued to do so will "burn" the head gasket.