Originally Posted By: Jetronic
Originally Posted By: Ducked
Originally Posted By: Jetronic
yes, the rockers would be...
so where's the iron coming from? Did you do a compression test?
Compressions seem within spec, though I could only use the push-on conical adaptor on my cheapo compression tester (screw in adaptor the wrong size, not sure how they're specified but I'll try and source one that fits next time I'm in Japan) so not very accurate.
Would poor compression be much of a clue? I wouldn't have thought you'd get much magnetic steel into the oil from the rings (aren't they stainless anyway?) though I can't remember ever having put a magnet on one. The block is aluminium.
Linklng to that old thread reminds me that, despite all the metal in the oil, I'm not really sure how much of a current problem I have. This also drags us back onto the general topic of UOA interpretation.
When I took the oil pump off there was a sludge-filled casting void in the base (maybe 20 mls, though I didn't measure it.) This may not have been the only one in the engine, and I doubt this feature is unique to this engine design.
It seems to be a tacit assumption that UOA data refers to changes in the preceeding OCI, with a (probably uncertain, since this varies) allowance for residual oil from the previous fill.
However, if the engine can store contaminants in a concentrated form, and release them later, it becomes much harder to work out what is going on. Contaminant release might be influenced by usage pattern, oil detergency or viscosity, for example, but these would be "legacy" contaminants, unrelated to the current status of the engine.
I havn't seen this possibility discussed, and wonder if its of general significance.
An aluminium block will have (wet or dry) iron sleeves, espevially those older engines. The newer engines could have a special alloy where the sleeves would've been. Rings aren't stainless.
The amount of iron you describe must come from somewhere. If it's a cam lobe, you should be able to see it. Since you can't see it, rings or liners, or even wrist pin is possible. I'd possibly consider a partial rebuild if it was my car, depending on the issue. If the liners are scored, I wouldn't do it.
Well, as noted above, the car has only scrap value, and, while I'd like to keep it going as long as I can, I may have to leave the country in a year or so, so sinking even more time and/or money in it doesn't make sense, especially without a specific diagnosis. I've probably already done more exploratory surgery than I should have.
As also noted above, I'm not sure what the current status is, because I think the engine stores contaminants, both because the sump doesn't drain well (theres a lip around the sump drain hole) and because there are casting voids.
I wonder if this is a general issue for UOA interpretation?
IF I have time I'd quite like to look into quantifying and perhaps characterising the metal, to give me a handle on the current status, and because it'd be an interesting "home science" project.
