I worried it was doomed. My coworker Bradley Brownell had called me from the roadside telling me my “Holy Grail” 1993 Jeep Grand Cherokee had a massive oil leak, and that he had been trying to replenish the engine as quickly as he could. But inline-six had run low, Brad was in the middle of nowhere, and he had no oil on hand. I advised him to limp the Jeep to the nearest town — a call that I worried had ruined my Jeep.
After Bradley had completed his trip from his hometown of Reno — where he had purchased the rare, base-model manual transmission Jeep Grand Cherokee on my behalf — to my place in Michigan, I took the pipe fitting that he’d used to plug the leak out of the engine. In its place, I threaded in a new oil pressure sending unit, and then I conducted an oil change, sending a sample of the used motor oil to Blackstone Labs.
Blackstone’s report concerned me, because despite Bradley having poured in at least 18 quarts of make-up oil, the oil that I had drained came back with elevated levels of Iron.
“Iron is still high enough to mark...steel parts are the main area of concern,” the report reads:
I sent this report to Dr. Andy Randolph, the technical director at ECR Engines — a NASCAR engine developer based in Welcome, North Carolina — and someone with plenty of industry engine development experience. Given the decent compression readings I had discovered using my compression tester, and given the good oil pressure the engine was making (and the lack of bearing material found in the oil sample), we concluded that the biggest concern was the camshaft.
“[The good compression] says it isn’t the bore. You’ve got oil pressure, so [the bearings are probably fine]...all you got left is the cam-lifter interface,” he told me. “It’s either that or nothing.”
Had running the engine low on oil worn down the cam’s protective outer hardness layer? Were those bits of camshaft that Blackstone had discovered in the oil?
To find out, Randolph suggested I send another sample to Blackstone after a few thousand miles. If the cam’s hardness layer has been compromised, then cam wear will not only remain high, but it will accelerate, and I’ll see even higher levels of iron in the oil.
I took Randolph’s advice and sent out a sample after 3,000 miles. The results just came back:
“Iron looks much better in this sample,” the comments begin. Not only that, all contaminants read below average for a 4.0-liter Jeep engine that has run 3,000 miles.
That’s fantastic news! My camshaft isn’t doomed! In fact, it looks like my engine is downright healthy! It makes great compression and solid oil pressure, and it isn’t wearing down faster than it should. My beloved Holy Grail Jeep Grand Cherokee’s 126,000 mile engine is probably only halfway through its life!
As for where that iron in the previous sample came from? I’m not entirely sure. Perhaps it was a product of the vehicle not having been driven a long distance in quite some time? A sitting engine can lose some of its cylinder lubrication, and that can lead to increased wear? Who knows. Or perhaps it was related to the oil geyser; in any case, it doesn’t appear to have been a big deal.
The report wasn’t perfect, though, with Blackstone writing: “We did find quite a bit of fuel in the oil this time, though...fuel is high enough to show a possible fuel system issue.” This isn’t a huge surprise, as I have noticed a slight stumble at idle. I’ll run some fuel injector cleaner through the fuel system, though I bet the real issue is a bad sensor somewhere. The big exhaust leak in the manifold could also be throwing off my O2 sensor’s reading, causing my engine to send too much fuel to the system. In any case, I’ll get it solved.
Before I conclude this article, I have a random question for you, my dear reader: What do you think about me painting the lower part of my front and rear bumpers red?
That way the red at the bottom parts of the doors/rocker panels continues on to the bumpers. It would lose me originality points when I show this Jeep at the Concours d’Elegance, but I kind of dig it? Anyway, it’s just a random idea...