Cracks in the timing cover...

Hi all, I'm a long time lurker, but this is my first post asking for help! I am in the middle of a rebuild of my 2004 Tacoma's 3rz-fe 4 cylinder, and while I'm cleaning up things and getting them ready to reinstall, I noticed a small spider web pattern of cracks around what appears to be a casting point on part of the aluminum timing cover. I'm wondering if anyone can give me an opinion on if this is a "must replace" situation, or if it's maybe marks from when it was cast? It appears to be on the oil return for the oil pump right beneath where it outfeeds to the block. Obviously if this were to fail I think I would lose oil pressure, But really I'm wondering if I have to spend the 300 bucks to redo this as well... If anyone has any opinions, or knowledge of seeing this o previously other timing covers that would be great, I appreciate any help! Cheers- Christian

 

I would definitely replace that. Some of those cracks propagate almost entirely across the surface.

 

Upon further inspection, it appears to be a spring loaded pressure relief channel that only is in use during what I guess is overpressure type situations? It looks like some type of pressure relief/recirculating valve.

I think you're right, peace of mind says 300 for a new cover and oil pump no big deal. Oh man, how the hundreds have added up in this rebuild, though! Gonna be sweet when I'm done. Cheers

 

Yeah, there's no way I could sleep at night knowing I put something like that back in the truck with so many cracks.

I find the best way to budget for these type of projects is to just not keep track of how much you've spent, lol...

 

You should start a build thread. I'd be interested to see your progress and always learn a thing or two! Cheers!

 

Are those actually cracks, or are they from the molding process? I'd clean them up and be sure. I've seen a lot of things that look like cracks, but aren't.

 

they look like they're emanating from that plug in the center.

I guess to be sure you could grind/sand down a couple of those and see if they are just superficial molding marks or something.

They look like cracks to me. Wouldn't be the first time I was wrong, though...

 

I just looked at the water pump I pulled off and they're all over the place, and they look just like that. They're either mold marks, or my water pump was about to break into 100 pieces.

 

I don't remember my (new) water pump looking like that.

 

But if you look at some of the "cracks" on the left side of your first pic, they look to me more like mud cracks or something like an orange peeled painted surface. Possibly hairline fractures.

It's a difference between raised ridges and incised "cracks". A quick filing and a polish could help see which is which.

 

Yeah its hard to tell from a photo. If I get back out to the garage tonight I'll do some more investigation.

 

Good call, I'm going to sand some of the cracks down and see what I see.

 

If you look where I am pointing in the picture, I found identical ridges that don't pass through as a crack. On the left you can see where I sanded the original area of concern, and while some of the spots go deeper than the surface, the other half seems to be solid aluminum. So, my plan is to roll with it,and I will live my life always ready to cut the keys off if I ever see the oil pressure drop! Thanks for the idea and the heads up everyone. I will try to get a build thread together and I'll post a link to it when I do. Cheers

 

They look like casting marks to me. As 0xDEADBEEF showed on his water pumps. If you look at the Tcase and transmission housings I bet you'll see the same thing.

 

Here is my t case. I believe they represent surface cooling of the metal when it is poured /injected in the molds. Pour some hot wax on a cool surface and peel it up once cool. You’ll see lots of imperfections