TT Teardown, Lots of ?s

[schwar74]

Well, I took the plunge a week ago and went for a TT, a 1990 auto with 165,000 mi. The body is in fairly good shape, it has chrome stock wheels, which I've always liked, and the interior other than the seats is in good shape. I have a 90 NA 2+2 that I bought about 3 years ago, but it didn't take long after I bought it to want to take a step up to the real deal. My plan is to eventually sell the NA to pay for the work to update the TT.

I bought the car with a knock ($1300) , but I'd always wanted to pull an engine and go completely through one, and thought this would be a good chance to do some learning. I'm definitely not a power junkie. Its as much about the process as having something insane as the end result. I'd just like to have a good running basically stock car that has some snort, so I definitely don't want to go crazy with performance mods and replacement parts if I don't need them. If my post is rambling, I apologize . . .

I spent the last week taking it apart and reading, reading,reading. Things went smoothly for the most part.

I got the motor out without too much trouble, and found a trashed bearing on the #6 piston. It had done quite a number on the rod and cap, as well as the crank.

This brings up question #1:

How repairable is a damaged crank? I know the rod and cap should be replaced, but do I need a new crank as well?

Here's a pic of the damage:



Is there an easy way to tell if it is too far gone to machine and polish back to usable condition? If so, how does one decide which bearing grade to use?

I read somewhere that grinding on a boosted crank is a recipe for a catastrophic failure. Is there truth to this?

Question #2 - The rod and cap are obviously trash. Am I better off to use the same piston (since it "fits" the cylinder) and just replace the rod and cap? Or should I buy a whole piston/rod/cap assembly?

Question #3 - The guy said the dipstick was popping out. I'm assuming this means the PCV wasn't functioning. Is this a sign of another issue?

Question #4 - Looking at the heads, There are no obvious issues with the cams or valves. Should I even mess with tearing them apart? Is there a way to do a better job of checking things out without taking them apart> How valuable is it to try to rebuild the lifters? Is it worth the extra time/work to do so?

Question #5 - Can I reliably assess the turbos with them out of the car? Can I tell if the seals are bad? The driver's side smoked exhaust a little bit, but I didn't ever rev the car up enough to develop boost due to the knock. Who's used rebuilt vs. new ones? Is there a reliable rebuild shop that is recommended?

Question #6 - So I did have one issue with the engine pull . . . . I dropped it Don't ask how, just stupidity. It was probably ~2 feet off the ground at the time. Of course the oil pan now has a nice dent in it, and the end of the oil sump is a LITTLE misshapen. Who's hammered theirs out? Is this way to big of a risk? Should I just buy a new one?

Question #7 - It has new style injectors/connectors, but they're pink. I was thinking that the 270cc injectors were pink? Any ideas on this?

Other than the piston/crank issue, I was planning on new engine seals, timing belt replacement, plenum coolant bypass, hicas delete, transmission cooler and possibly downpipes (exhaust is basically a cheap straight pipe). The EGR, carbon canister and AIV have been deleted already. What else should I look at doing? I thought about a manual swap, but I don't think its in the cards at this time.

Thanks for the help guys!

I'll post more questions as I think of them.

[BlackWidowZ]

I would keep the 2+2 and use the parts from the TT and convert the 2+2 to a TT. You will have a better car that accelerates faster, gets less tail happy and corners better.

[NolimitZ32]

Better is completely subjective, thats I'll say about that.

1. Only way to tell if the crank is usable is to mic it and let a machine shop have a look, only a professional will be able to tell you if its salvagable.

2. Again you will need to gauge the bores and mic the piston as it is recommended to hone your cylinder walls during a rebuild to get spec'd compression. Most likely you will be able to reuse the piston.

3. Very likely that the PCV is clogged.

4. I have never rebuilt anything in my top end but then I never had any lifter tick or other issues *knocks on wood. I guess if you have the time and ability it can't hurt.

5. You can assess for shaft play, generally too much shaft play means bad seas well. I don't know of any rebuild shops personally but you MUST have a shop that has a high speed balance do the work otherwise your rebuilt turbos wont last a month. Generally the best course of action is to buy new CHRAs and swap your comp and turbine housings on. With used units you are obviously rolling the dice and buying a full new unit is not necessary when you can easily save yourself a bit of cash by going the route I mentioned previously.

6. Generally due to the internal baffeling in the pan you wont be able to knock it out. My pan on my JDM engine was dented (like most) when it arrived, the way it was dented however allowed me access from inside to knock it out and I have never had starvation issues, this again should be judged on a per case basis but going off what I imagine would be the damage done by dropping the engine from 2 feet I would say you should really consider getting a new pan.

7. I would be willing to bet that the pink tops you have a Venom/TLF aftermarket redrills (ebay special) I ran some for a while and they worked ok, definitely not as nice as original stockers or nismos, or factoy JECS (not redrills)

Also, I fixed your picture link, next time use the IMG code available on photobucket and paste it directly into your post.

[schwar74]

Nolimit,

Thanks for the thoughts. I had a machine shop look at things today, and the crank is junk. Plus, they found some damage to all the pistons and the cylinders would ideally be bored .25mm. So now I get to decide if I want to buy stock pistons or jump up to wisecos for peace of mind. I've got some feelers out looking for a crankshaft replacement. I'll see what I can come up with. He also recommended a whole new oil system (pump,cooler, etc) due to the high likelihood of there being pieces of the shredded bearing everywhere in the oil system.

They thought the oil pan was salvageable, which is good news. Looking more closely, the damage is just where the sump sits, so I can get to it fairly easily and straighten it out.

I haven't gotten a chance to inspect the turbos at all, but rebuilt ones aren't terribly expensive, so I'll probably just go that route.

I'll keep updating.

[NolimitZ32]

Sorry to hear that, the good thing is that the VG30DE/DETT have the same black, crank, and rods so if your bottom end is trashed you should be able to find replacements quite easily. GL

[Bigred*]

If your not planning on a high hp build I'd say just get a stock pistons rods, had I gone through my machine shop it would have only cost me $200 for stock pistons and rods, but i want to build high eventually so I dropped $1000 on wisely and eagle stuff.. On a side note I have some nice vg30dett rods and pistons with 130k in good use able condition.
I'd also recommend replacing the oil pump while your in there, if we're only last a few more thousand miles you have to completely tear down the engine to get back to it, and with shredded bearings who knows what the flakes did to it

On the turbos if you grab the turbine and has any wiggle side to side or up and down then your seals might be gone.. If it's very minimal then you might be ok, because once the oil is flowing through them it centers the shaft while they spin.. Mine was so bad that my blades were actually contacting my side wall.. Good luck on it!

[schwar74]

So I'm on to plan B,

I picked up a used motor this weekend, and am getting started with going through it. Its apparently been sitting for about a year. But so far, it looks nice and clean internally.

So on to more random thoughts and questions:

I'm trying to decide how far I want to go taking it apart. I've got the valve covers off, and things look pretty good on the top of the heads. And looking into the intake and exhaust ports, the valves look good. Should I pull the heads just to take a look at the valves? And to look at the tops of the cylinders? I was thinking about swapping in the lifters out of the heads that were on the trashed motor since in theory at least, they should still be fairly full of oil.

I removed the oil pan, and the bottom end looks good, with nothing metalic in the pan or in the sump screen. I was thinking that as long as all the rod bearings feel tight, I should be ok. Agreed? Is there anything else to check while I'm in there?

Is there any way to tell auto from manual cams besides the paint? Or aftermarket cams? Do I just need to mic the lobes?

Another nice thing about the motor purchase is I got another wiring harness (to hopefully salvage some better connectors), some exhaust components and a nice polished plenum, as well as some powder coated throttle components along with it. And an extra set of heads. So now my garage is full of parts.

I also got a hicas delete kit in the mail as well, so I have that to install also.

Any other thoughts/ideas?

Thanks!!!

Scott

[schwar74]

Update . . . . Finally was able to start it last night. Pretty excited to say the least.

I ended up rebuilding the used motor that I got. It didn't really need much as it was in pretty good shape, but I wanted to be sure. The block was dipped, the cylinders honed, heads checked, and then it got new bearings and rings. I cleaned/serviced the lifters per Ash's writeup on TT.net. I also bought a replacement fuel rail from Bernie with new style stock injectors.

Everything went fairly smoothly overall. I failed to recognize that the head bolts are different lengths, and got a short bolt in the wrong hole, which messed up a little bit of the threads, but things torqued down fine.

I bought some good used turbos that were pretty much within spec as far as shaft play was concerned.

The cooling lines were rerouted because I deleted the cooling lines from under the plenum.

I think there's an issue with the inhibitor switch/neutral safety switch (auto transmission),as I couldn't get the starter to engage. The starter relay is not getting any signal with the key in the start position. If I jumper the big connector coming from the starter relay, it cranks just fine.

Theres a pretty good puddle of power steering fluid under the pump today. I'll have to get that figured out.

But its good to know that its alive, and that this whole project now has an end in sight!

Scott