Ya know, GD, the more I think about it, the more I think somebody did adjust those valves on yours. Was it lacking in power at all? And was there any carbon on the valve faces? I have had valves hang open before, and it sounds like a knock if it's just open a hair. Plus, there shouldn't be two wear spots on the cam, there shouldn't be any wear at all on the base circle. Maybe on the ramps and the nose, but that big shiny scuff under the left hand lobe is all wrong-

Well - can't say about what was done to it by the tractor mechanic previous owner (no - really he was an honest-to-god tractor mechanic ), but it had excelent power the whole time I ran it. I could burn em in first and chirp em into second pretty easily. Top speed was well over 95. I personally adjusted the valves about 20,000 miles ago when I had .025" taken off the heads (there's a special adjustment for this situation), and I adjusted them again right before I pulled it on a sugestion that I may have not got them adjusted right that first time because of inflation issues due to the heads being off. Didn't change anything - the idle was still just as bad, and the knock never changed. Heads and valves look alright - no evidence of a problem there. Pushrods are all straight, etc.

 

I pulled each plug wire with it running and it didn't make any difference in the knock. FSM points to the cam journals...... I don't know what I can do about that tho since they don't have bearings. I'm hoping it's not that or I'll have to swap blocks. Still gotta get some plastiguage so I can check the cam journals.

 

GD

The cam from my old Prelude had similar 'erosion' on the edge of a few of the lobes. However, whenever it was running the tacho stayed in the red. It was given an absolute thrashing and i never checked the oil. Basically everything was wrong, no air filter, no warm up, poor lubrication and overheated daily. It didnt idle either but i dont think i can blame that on the cam. I dont know what caused the metal to pit like that, but its the only time i've seen it happen without saltwater getting involved.

Looking at the problems on the outer sides of the lobes it looks to me that the cam was poorly cast.

Looking at the problems on the outer sides of the lobes it looks to me that the cam was poorly cast.

 

Yeah - it almost seems that way to me as well - it's an '85.... I wonder if the quality control on the EA81's went downhill after the EA82's came out.... visualize a situation where all the important managment and quality control inspectors (the good ones anyway with mega experience) get shipped over to a new factory floor to jump start production of EA82's.... hhmmm - hard to say. I have the cam from an 89 hatchback engine out and while it does show some pitting, it doesn't have the severe edge deterioration the one from the Brat shows.

 

GD

My first impression was a poorly sintered sintered-metal part (I know it isn't, but couldn't think of anything else that would like that). Certainly didn't look like wiping wear.

Regarding the clearences, the only way to check them is using a telescoping gauge and micrometer - which if you ask me is easier than messing around with plastigauge anyway!

 

This is slightly more difficult for the mains than for thei big ends, although from memeory, wont the green plastigauge do the mains, just not the big ends?

Ok - I finally got it torn down to where I can measure stuff (the wrist pin access plug under the water pump was giving me a hard time). I bolted it back together and measured stuff up with a digital caliper.

 

The cam journals are spot on - no news there - the cam being iron and the case bearings being aluminium and all. The case looks good too - some slight wear but nothing bad, and nothing that looks too far out of spec. I think the strange edge wear is just casting problems, but they don't seem to be effecting engine performance, and the rest of the cam wear doesn't seem bad at all really. Looking closely at the wear pattern shows the brunt if the wear is actually happening on the opposite edge of the lobes, and the lifters look decent with only minor pitting.

 

The mains aren't looking so hot. The crank looks to be about .04mm under the smallest spec - all of them are running about 49.91mm. Book calls for 49.957mm - 49.970mm. Looks like the bearings themselves are worn as well. All in I'm guessing the oil clearance to be somewhere around .075mm. Max allowable by the book is .025/.030mm....

 

What I'm looking for is the "source" of the knock. I want to make SURE I get the cluprit the first time. Who thinks that .075mm would give me the slight knock at warm idle (didn't do it cold, only warm after the oil thinned) that I could hear easily with the oil fill cap off, and feel in the shifter?

 

The knock was a "deep" tone - not something you would expect from the cam or valve train as it didn't seem they would have the mass - it wasn't the light metallic knock of a rod, and it wasn't the tick of a lifter either.

 

So what's the consensus?

 

GD

Sorry for being so "last-Millenium", but that works out to be just under 0.003inch, right? How was oil pressure at warm-idle? Seems to me with showing decent pressure 3thou isn't that much... but maybe the tight clearances are how Subaru gets away with low oil pressure/flow at idle.

 

Was there a difference in clearance front/mid/back?

It's very tough to measure - my digital caliper only has accuracy down to .001", and to .01mm so..... the journals on the crank were pretty much all right around 49.90 - 49.91. There didn't appear to be much difference between the three. The bearings are a lot harder to measure, but the plastiguage seemed to indicate some were more worn than others - center and rear were definately not as crushed. Looked like the front was around .075mm clearance, and the rest were a bit more. Possibly as much as .1mm at the rear.... so maybe around .004"....... 4 thousandths cause a noticeable knock? These tollerances are maddeningly close

 

Engine has a brand new oil pump, and new sender - showing 20 - 25 psi hot idle, but I was running 10w40 and sometimes 20w50 in it because I feared the mains were causing the knock. Lets call it 20 psi with 50 weight which would probably put it a bit lower than that with 30 weight - maybe in the 15 psi range. Considering the pump was new and OEM, I'm guessing that to be a little low....

 

GD

Ok - closer inspection shows the front and rear bearings to be about the same - almost exactly 55.00mm on both. Crank being right around 49.90 that gives both around a .10mm clearance - far beyond spec.

 

The center bearing seems to be the interesting one - my measurements of the bearing show it's right around 55.10mm. That gives the center bearing an oil clearance of .2mm. That may be the source of my knock right there.... what say you?

 

GD

Just re-read the whole thread, again. Didn't see any mention of crank end-play. Isn't the center main bearing the one that is the trust bearing? (No book in front of me, so I can't look for myself). Worn thrust bearing will allow the crank to "walk" fore-n-aft while rotating. Makes a pretty good noise which is a bad thing, can be heard thru fill tube and felt in a manual shifter.

 

My first thoughts on the cam pics was bad metal from the get-go also.

Good thought - checked the thrust and there is no play there at all.

 

Upon further inspection, the #4 rod bearing looks pretty wasted. So it's got bad mains, and one bad rod bearing - probably the source of my knocking. I'll get a measurement of that here shortly....

 

GD

Looks like the mains are about .10mm oil clearance (possibly more on the center bearing - book max is .025mm), and the #4 rod bearing was pretty out of round - with a max oil clearance around .13mm. The horizontal surfaces of that bearing have actually begun to wear through the bearing surface to the softer metal underneath. Book max on the rods claims .10mm max but even that seems like a lot. At any rate all the bearings are obviously way out of spec - in the case of the mains 4 times over the max, and possibly more in places. Probably safe to say my knock was one of those....

 

So next step is to degrease the entire mess, and start the reassembly with my new parts.

 

GD

Hmm, they're some fairly nast clearences...... You'll want to check all the oil galleries well - 20psi at hot idle sounds suspicously high for an engine in that condition - when my ea81t was in similar condition it ran at about 3psi hot idle with a new pump.

Even now i've rebuilt it it doesn't sit that high.... although cant really compare the two different engines.

The EA81T is almost exactly the same except for the pistons, and the head castings. But all my EA81's have run right around there. Just put a used engine in my wagon and it's running 20 - 25 hot idle, and 50 at cruise. New pump, and I'm running an autometer guage and sender so.... have you replaced your sending unit? I also have an EA82 (carb) and it runs about 15 - 20 hot idle, but needs an oil pump reseal I'm sure.

 

I just started cleaning it, and the inside of the engine isn't dirty - a thin layer of cooked on oil, but nothing bad. Oil galleries look good. I'll blow some air through them to be sure though.

 

Was your EA81T making any knocking noises?

 

GD

I'm using a mechanical gauge.... I'm thinking my pressure is lower than a standard ea81 or an ea82 because of the way the turbo oil supply is hooked up - staight off the pump.... but who knows, as long as it stays above 10psi i'm happy enough.

 

Yeah it was knocking quite a bit, mainly a bad rod knock but i thought i heard a deeper, main bearing sounding knock on a few occasions.... I don't blame it tho with such poor oil presssure.....

I've noticed that even with bad mains or rods if you have a new, sealed pump the pressure doesn't drop much since the sending unit is right there next to the pump. So you may be onto something with the oil supply. I have the stock pressure guage in the Brat, the Autometer in my wagon, and a Wall-Mart mechanical cheapy in my EA82 sedan, and they are all (more or less) in agreement on pressure.... seemingly regardless of the engine condition by the looks of the bearings in this one. I guess I'll see when the new bearings all go in and she's started.

 

GD