[Pooch]

ok, here it is:
my wife's 1990 crown vic was starting to knock a while back. it would only do it just when first started cold, maybe 5 or 6 taps and then it would shut up. we knew it was going to need a rebuild soon, but I told her to drive it, and if it ever DIDN'T stop, shut it down and it was time to rebuild it. well, that day came, and I pulled it apart. meantime, she borrowed her mom's car till hers was done. well, it took me about a month and a half of weekends and evenings, but I got everything done. you don't know how nervous I was the first time I hit the key. but it fired up, ran just like it did before, heck, I even had the timing spot-on! I was pretty happy, and even a little impressed with myself. so she drove it around town for about 3 weeks, then we decided to make a 200 mile round trip with it. I checked the color of the oil before we started, and decided that after the trip I would change it. the trip went smoothly, not so much as a hiccup, and the day after we got back I went ahead and did the oil change. then everything went to sh*t. when I put the engine together, I put 10w40 in it, and I decided to change it with 10w30. well, as soon as I changed the oil, it started to knock again. I changed it again with 10w40, and it quieted down for a week, but now it's back. you have no idea how pissed I am about this. why didn't it do this earlier? what changed? NOTHING! JUST THE OIL!! I'm going to start building her a new motor from scratch soon, so that if hers dies, I can just replace it, and she'll only be down for 3 or 4 days. I can't even explain the frustration I'm dealing with over this. thanks for listening, I just had to get this off my chest.

 

[psguardian]

Might your tag line have something to do with it? It sucks for sure, but sounds like you may have done a minimal rebuild & got bit in the tail feathers... Used the old oil pump, started up dry without priming the oil system, didn't get the rods machined, didn't get the block machined, didn't bore match the pistons, forgot a thrust washer on the crank.

Any of these ring true? These all sound like a reasonable short-cut, until the knock returns. Not trying to be rude, or poke at you... Just hoping to talk through it & see if there was anything missed/skimped on that might account for the knock.

~psguardian

 

[Pooch]

Might your tag line have something to do with it? It sucks for sure, but sounds like you may have done a minimal rebuild & got bit in the tail feathers... Used the old oil pump, started up dry without priming the oil system, didn't get the rods machined, didn't get the block machined, didn't bore match the pistons, forgot a thrust washer on the crank.

Any of these ring true? These all sound like a reasonable short-cut, until the knock returns. Not trying to be rude, or poke at you... Just hoping to talk through it & see if there was anything missed/skimped on that might account for the knock.

~psguardian

new oil pump, crank turned, assembled with white grease and primed the oil pump first, did not machine the block or rods. thinking about it now, I wonder if the original knock could have egg-shaped the big ends of the rods to a small extent, causing the bearings to not sit perfectly. I didn't plastigauge it either, and I know I should have. a guy at work has a factory crate engine that has about 10,000 miles on it, but it's been sitting in a corner of his garage for 10 years. he'll let me have it for $100, so that would be a good place to start building a new engine. I have to wait until I buy a house, though. we've been looking for a while, but I'm not going to do it where I'm living now. 2 reasons: no room, and I don't want to try to move an engine later. just hope it holds out for a while.

 

[Pooch]

I actually wondered if the machine shop turned the crank wrong, but that would have been an issue from the second I started it. when I replace the engine, you can bet your @$$ I'm going to tear into the old one to find out what's up.

 

[psguardian]

My money is on egg shaped rod ends, or main bearing seats out of true (warped block). The 10k motor sounds like a PERFECT candidate for a full block up rebuild. Hope she can baby it until the house & rebuild are done.

~psguardian

 

[Airhead rider]

Yup, the rod big ends are stretched. It knocked before, and that hammers out the big ends. You put in new bearings, temporarily tightening the tolerance until the stretched rod bore had a chance to beat on the new bearing, once again increasing the tolerances enough to knock.
I've said it before and still am a believer that bearings don't just fail, something causes them to fail and until for identify and fix that "something" they will continue to fail. Bummer, all that work and expense to be right back where you started.
On a related note, that's also what scares me when someone has a vehicle for sale with a "rebuilt" engine. Until you know who rebuilt it and the specifics, I'll not put much value on that statement and in fact may reduce the vehicles value.

 

[Pooch]

yeah, it sucks to be into it a month and a half & probably $1000, just to be right back where we started. but on a positive note, at least things won't be all gooey when I tear the thing back apart again. I hope the other motor doesn't have rust all over inside, but I think since it's been in a garage the whole time, it should be fine. this guy knows his stuff, so hopefully he stored it appropriately.

 

[psguardian]

Just remember to send the block in for cleaning & measuring. If it passes spec, then move on. If it doesn't, make sure it gets the services it needs. (my trip to the machine shop was spendy but worth it)

~psguardian

 

[Pooch]

here's hoping we find a house soon. :clock: