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96 2.5l OBW head gasket project


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It might just be my screen, but I can't really tell from the photos. The typical place that the headgaskets fail is on the lowest point of the cylinders into the two small water ports. These water ports would make the "smile" of a smiley face if they connected, and the two lowest valves would make the "eyes" of the smiley face (if that makes any sense). On mine, the failure was on the passenger rear cylinder, and a little bit on the front cylinder. The driver side was fine. There was black carbon on both the head and the block going through the area of the metal fire ring and extending all the way to the 2 water ports. If you leave your cylinder heads intact as-is and bring the old gaskets in, the machine shop can probably point you to the failure point(s).

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1stSubaruParts told me that I needed the O-rings for the coolant crossover pipe. Is this just a prudent change while it is easily accessible?

 

I'm going to replace the lower t-belt idler and the geared one, too. Yikes, they are expensive!

I guess they are a pain to replace the bearings...? I remember this question being thrown about for the EA82.

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After I took the gasket off the head, I could see the slight carbon tracing from the cylinder to the coolant passage on cylinder #1. I put my ground straight edge on it and it looked pretty good. I'll see what the machinist has to say.

 

I put my order into 1stSubaruParts which came to $400!!! I decided to replace the lower idlers which were noisy, so I guess that really tipped the scale... I guess it's not bad since I had the car given to me. They did say I didn't need the O-rings for the cross over pipe.

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  • 2 weeks later...

I don't know if anybody is still paying attention to this thread, but I'll ask my next question anyway and see...

 

The backing plate on the oil pump is on solidly. I can't budge the screws and assume that they were thread locked. Is there any reason to take this plate off?

 

I will be getting the parts in the mail tomorrow so I'll be starting to assemble the engine tomorrow. I have the "official" manual which includes all the torque specs for the parts.

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Hello,

 

Ok, I'm letting the oil pump alone. I got the parts in the mail to continue, but they sent me the wrong T-belt idler. They sent the tensioner. I guess I'll just use the new one they sent as the old one is a little noisy, too. Better safe than sorry(+$70)?

 

Next question- I have been cleaning the engine block surfaces to receive the heads/gaskets. The heads have been machined. The surfaces of the engine block has some patterns from the old gaskets and most of it comes off with 600 grit W/D lubed with WD40, but the pattern is still visible faintly and there are surface imperfections that seem origional to the surface.

 

How clean is OK? And what imperfections are permissable? I'm concerned that if I get them sparkling, they will be not be flat. I can post photo's

 

thanks

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Yes, I am. The t-belt only had 40k on it , but I'm still replacing it....

 

600 grit is pretty fine??? and I hope the WD-40 keeps any grit in suspension. I also will vacuum and use compressed air for final clean-out. Sound good?

 

I just realized tonight I forgot to order the t-belt, so I'll call 1stSubaru tomorrow and have them add the t-belt to the idler shipment.

 

I hope to put the heads on tomorrow if I feel comfortable with the surfaces ( see previous questions).

 

thanks,

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Hello, I've been reading about the MLS gaskets and their needing almost mirror surface? Then, other opinions in threads mention gaskets needing something to "bite" on.

 

Here are some photos of the engine block that I'm preparing. Do the corroded area's need to be cleaned up more? There seems to be outlines of the old gasket and some corrosion there. It's not reall too deep. I really don't want to redo the gaskets anytime soon...

 

Opinions?

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Take other folks opinions too, but mine is you never get those areas quite perfect with decking the engine in a machine shop. The plate glass method gets it as flat as you can without decking, but tiny corroded areas are often still visable and feelable.

To be 100% certain it is best to deck the block or resurface it. On the other hand since the gaskets seal 99% of the time most head gasket jobs only have the head resurfaced.

I only had sealing problems in two engines in the five or six hundred I did as a mechanic.

If is an area over a coolant passage it's a no worry anyway unless the edge of the gasket overlaps the corrosion.

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When you rebuild an engine you have the head surfaces of the block remachined. I have seen two systems for this. One is to mount the block in a fixture that holds it precisely in place and mills a new surface. Another system which is more modern, drops the block deck surface on what looks like a giant ultra flat belt sander.

When you remove surface material from a block to straighten it, clean it, or raise compression it is often referred to as decking the block.

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Talk to your machine shop and see what they recommend. They are going to be the experts.

 

I bought a 3M "scrubber" wheel attachment for a drill. It's made of plastic and has a bunch of bristles on it. I used that to clean all the crud off, then I sanded with WD-40 soaked 600 grit just as you did. These blocks are aluminum, so you want to be gentle. Even the plastic scrubber wheel will leave very faint "marks" on the surface, but a few swipes of sand paper remove it. I used just enough pressure with the scrubber pad needed to remove the crud. Too much pressure starts bending and warping the bristles on the disk, and then it doesn't work so well.

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Hello, I cleaned up the engine block with 320-400 W&D backed by wooden blocks. I am a musical instrument maker and can true a block of wood to good tolerances with a finely tuned plane. I also kept track of the trueness of the block with a ground straight edge. I got what I thought was a pretty good surface. I also dressed the head surface a little after reading about surfaces for MLS gaskets.

 

I cleaned up and did the torque sequence for each head. I will hope for the best and hope that this will last for the rest of the cars life.... We'll see...

 

I'm putting in the lifters and camshafts now and have to make sure they are in the proper positions before torquing the keepers.

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ARGHHHH!!!! one of the camshaft cap bolts snapped off while I was tightening it down!! I was going through the sequence as described in the manual and "tick". I remember they were fairly hard to break loose when I was taking them off. Looking at the long shaft, it makes sense. This was the first camshaft to be installed and I'm going to be paranoid with the rest. One thing I can think of is I was pulling the cam down a little bit with the bolts. I must be sure the other cams are seated in the lower(head) ways before torquing.

 

I guess I will have to drill it and try to easy out it??? These are hardened bolts?? and if that messes up the threads, helicoil it??? Do they make helicoil this small?

 

Any advice would be welcome....( I am so PO'd) time to back away from the tools...

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OK, I've cooled down and read up on screw extraction. It's time to find some left handed drill bits. I hope I can find them locally, tomorrow...

 

I have a straight flute extractor, but on advisement, I'll use that as last resort. I'm going to grind a flat on the sub surface stub and get a good center punch point and start drilling.

 

Wish me luck...

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