Brought the car in do a little more investigating and got a bit more bad news, though not unexpected. I had noticed while working on the radiator that turning the car over by hand didn’t reveal any real feel of compression so I finally got around to doing a leakdown test. I’ve never tested an engine that will run that’s as bad as this one. Most cylinders showed 50-60% leakage, but number 3 is about 80%. There aren’t really any noises coming from the intake or exhaust, and no bubbles in the radiator. But air sure rushes past the pistons into the crankcase. There are a few possibilities here. It could be that the rings are a little stuck from sitting, or that they never got well seated after the rebuild. But a couple of Mr. Meyers diary entries from back in the day refer to piston slap and “whooshing noises” of pressure passing the pistons make me suspect that the pistons were never properly fitted after the last rebuild.
No reason to panic yet, but I’ll have to disassemble it to figure it out.
I got the turbocharger off, too. And I did it without removing the manifolds. There’s no doubt about it’s malfunctions now. The hot side was full of oil and burned, nasty smelling residue, and the side play in the shaft is so great that you can make the rotor hit the housing. I’ve not taken it apart to see if it could be rebuilt, because I’m not going to use that one anyway, if I can afford to save the engine. I’ve been handed a few turbos to inspect this week. Some of them are obviously not appropriate, but I have one from a Subaru, and another from a Saab with similar capabilities as the Dodge one that was on it. Both of them will offer MUCH easier packaging as they are shorter and lighter.
Once I got the turbo off, I could study that side of the engine better. I misunderstood the application of the famous stacked oil pump mod. I had thought that it just provided a higher flow to engine as a whole, and allowed a take-off to supply the turbo. Instead, it only supply’s the turbo and runs engine oil through a filter. I think that’s all OK, but I discovered that the oil pressure gauge I had been watching only monitored that part of the system. Does the original gauge on the dash show the oil pressure in the engine itself? I don’t know because I never looked, but obviously the engine isn’t devoid of oil pressure. I may get the car running again before I take it apart and hook a good gauge up to tell me what it runs just as further diagnostic information.
I also got a better look at the manifolds. And found a pretty bad leak on the intake side. There is a bolt missing that should clamp one side of the intake and one side of the exhaust. I don’t think it’s been on there since the turbo was installed because the two manifolds don’t line up well and the bolt hole is a bit hidden. I was planning to remove them and double check them inside and out anyway, but it probably explains the persistent high idle.
Not much more will happen soon, winters bearing down us and we’ve got garden to take care of, wood to get in and a deer to put in the freezer, hopefully. I keep finding myself out there late in the evening though. It sure is a fascinating project.
|Editor: I am certainly a better mechanic now then I was all those years ago… My guess is that the rings were fitted ok but are now shadows of their former self! Very curious to see. That was a junkyard turbo, and the demise of many was coking after rapid shut down. TO3 turbos from four cylinder mopars and parts shouldn’t be too hard to source. If you decide you need one, I might have one. If I remember, that one had water cooling. Later models didn’t. The advice was to let it idle for a minute or two before shutdown. Some say that using synthetic oil will prevent coking. You don’t have much to loose by trying it. You won’t know for some time whether that works.|
Boy, do I want to see inside there too! You can literally blow through the leakdown tester hose with lung pressure and freely blow air into the crankcase. Yet, after 3 or 4 revolutions a compression test shows 125 pounds or so on a stone cold engine, on all 6 cylinders. That’s why I asked if you remembered purposely using larger ring gaps to account for the boost. I’ve never seen anything quite like it. I’m setting up the car to run without the turbo and will repeat the tests on a warm engine.
Thank you for the offer on the turbo, I’ll keep it in mind. Holding a turbo off of a 2.5 liter Subaru is an eye-opener, though. Very similar rotor and turbine sizes, but pounds lighter and inches shorter. Funny that you mention coking, a friend just suggested changing to an electric oil pump for the turbo so that it could be on a timer and run for a couple of minutes after every shutdown. We’ll see, electrics and electronics are not my favorite solutions for most things.