PickleRick
Veteran Member
- Joined
- Nov 29, 2017
- Location
- Greenville sc
- TDI
- 05 GLS BHW sedan 5 speed conversion. BHW Carver SantaCruz in progress
Really? I would think cyl wash plus a head gasket leak would yield very noticeable differences between cylinders. My only experience with a bad diesel headgasket came from older direct injected kubota 4 cylinders. Knock on wood I've never needed reason to do a compression or leak down test on any of my BHWs.Just to be clear, just because I have not SEEN a failure mode of a BHW EGR cooler as you describe, doesn't mean it cannot happen. Every 3.2L diesel Transit's EGR cooler fails like. So many, Ford extended the warranty on them.
But, it is pretty easy to see... start the engine up cold, and the coolant bottle will right away start gurgling. There is also a combustion byproduct testing device (gas and diesel are different) that can be placed over the bottle to see if the source of the sudden extra pressure is from that, but that alone will not isolate an EGR cooler or head gasket.
Compression test won't tell you squat. The engine has PLENTY of compression, an allowable difference in percentage would easily eclipse the amount of combustion passing into the water jacket to build up pressure.
Pumping high pressure into each cylinder might, but again you'd need a LOT of pressure, well beyond what any normal shop air can provide.
As for leak down my shop compressor is capable of over 200 psi but the leak down tester i have (from kohler for gas engines) has a regulator on it in which you adjust the pressure down to get the gauge at a particular setting to start which is some 45 psi i believe. Because of diesel ring gaps many times being much larger what is unacceptable for gas motors is just fine for diesels. Not 100% sure of the diesel limitations for leak down % but i more or less just test all cylinders whether 2 or 8 and if all are about the same i call it good..if one or two reads 20% more leak down or 20 psi less compression than the others i know that something in there may need addressing .
What is considered good compression for one of these?