Motor rebuild or car sawp?

[Avispa]

Long post - bear with me here......

After 97,000 miles, 25k of which has been Whipple 2.3 blasted, my motor is getting sick. Definitely some exhaust getting into the water - open the reservoir when it's hot and the coolant is foamy and has a distinct exhaust smell. One or two cylinders misfire for the first 30 seconds after startup, and there is occasional detonation at full throttle. The bottom end is still solid; less than 5% leakdown, no blow by, doesn't use a drop of oil - the problems all seem to be in the top.

Talked to the owner of Pro Weld Performance for about an hour yesterday. A well done rebuild is going to be at least 6k (all new pistons, rods, valve springs, timing chains, pulleys, lash adjusters, etc.). The place formerly known as Tousley Ford isn't sure when new longblocks are going to be available even though their price is fantastic.

Here's the money question. There are plenty of low mileage cars out there for low 20s. Beside the motor work, I'm going to need about 3-5k in cosmetic stuff (some repainting, new seat covers and carpet and a few misc. interior items). So - keep the car and fix it or get a low mileage replacement car, put all my goodies on it and sell the current car returned to stock? Even with the motor issues I'm sure I can get at least 7-10k for the current car.

Thanks for your opinions.

 

[Nightmare90gt]

Why swap pistons and rods they are forged peaces

 

[Quick Strike]

Why swap pistons and rods they are forged peaces

I'm thinking at 97k it is time for new pistons and rings and the rods would be good to go with ARP 2000 bolts. I think you could rebuild if for much less then 6k: more like 3-4K at the most.

 

[Nightmare90gt]

Rings yes but pistons only need replaced if they are damaged or your block needs bored out. Don't forget if you replace anything on the rotating assembly it has to be rebalanced.

 

[gabe1530]

youd be better off doing a basic rebuild. i would replace with pistons but re use the manley rods. arp2000 everything and youll have an extremely stout long block.
now would be the time to do some port work on the heads and add some aftermarket cams if your up to it.

all the cosmetic stuff could be done over time. you dont need to drop all your money at the car at once.

 

[2face]

stay with your cobra rebuild motor for way cheaper plus ur exterior work like 10K -12k total !! you said 20K for newer car what then? tax an registration plus what ever else you gonna wanna do to it you did say keep ur goodies for ur new car did u mean sell ur cobra an get another cobra? how do you know the cobra ur gonna get doesn't have same issue or that they returned it to stock and are dumping car off!!! I'm just saying thats all ,good luck let us know what you decide

 

[Avispa]

Guys, I really appreciate your suggestions. Seems to be unanimous that I should keep the current car and fix the motor. That's they way I'm gonna go.

The reason for thinking about a replacement low mileage car is that, as 2face says, fixing the current car would be 10-12k all in. But remember I'd still have a tranny, differential, stub axles and wheel bearings with 97k on 'em, too. Swapping cars I would end up with all low mileage driveline stuff for about the same total money (not to mention less-used power window motors, electrical system, weather stripping and the whole shebang..you get the idea). I meant to take all the mods off my current car and put em on the replacement car - put my current car back to stock and sell it.

Pro Weld's owner basically doesn't want to let an engine out of his shop that isn't all new rotating stuff (except maybe for the crank), so I see where he's coming from. Lots of engine builders say, "my way or the highway", and I can understand that. Their stuff usually ends up on a drag strip or circle track somewhere and they don't want things breaking. Mine is my DD and I'm sure the original rods with new ARP bolts and a good shot peening would run another 100K without breaking a sweat. BTW, the original pistons aren't forged. They're hypereutetcic castings, which is why detonation or running lean under hi boost is usually instant death for a stock motor. I'm hoping the cylinders don't need to be bored oversize, and would only need a glazebreaker honing. If the short block is in the shape I think it is, I should be able to get by relatively cheap.

Gabe, Pro Weld was going to include at least a bowl cleanup and port match on the heads and lower intake. Porting is really not necessary and I can't see any reason for aftermarket cams. I'm running stock heads, lower intake and exhaust and could still put 612 to the tires. I can't put what I have to the ground as it is.....lol

I can afford to do all the stuff to my current car, but it's never a good idea to fall in love with a particular car - you have to do what make the most sense money wise. 2face made the best point, though. With another car it's impossible to know what you're getting, even if it's a low mileage one. Even with all the miles on my driveline stuff, I do know they're all in great shape.

That's why I love this forum. Great people willing to help out when ya don't know what to do. I will keep y'all posted.

 

[cj428mach]

I swapped from an 80k mile terminator to a 7500 mile car as I was kind of in the same position as you although my higher mileage car wasn't in need of an engine. I knew that some day I'd want to freshen up the drivetrain in the high mileage one as well as get the front clip repainted, IRS rebuilt etc.

I eventually came to the conclusion that it would probably be about the same money to just buy a lower mileage one. So I bought my OW car and sold my old SB car. I took all the mods off my SB car and swapped them to my current one, and I have about $8,000 in the swap. Now I have a like new terminator thats going to be ready to go for years/miles to come and its in my #1 color choice.

 

[Nightmare90gt]

You have a 03 cobra right if so and it's the stock block with rotating assembly it most certainly has forged piston made by mahle correct me if I'm wrong on the manufacturer. The rods will be h beam made by Manley and a Kellogg forged crank.

 

[jjk23]

You have a 03 cobra right if so and it's the stock block with rotating assembly it most certainly has forged piston made by mahle correct me if I'm wrong on the manufacturer. The rods will be h beam made by Manley and a Kellogg forged crank.

+1

 

[hotcobra03]

I would think buying a 13 yr old car is risky even with low miles. .

sitting that long things still go bad...plus add the common issues that will happen..when used..

ours is stock...just turned 362k...under 100k is nothing..

Drivers head has been our only real engine issue..3x

 

[Ponyracer1]

I'd say alot depends on how happy you are with the car. Do you want a diff color? etc? Yes you have a history with yours and a new low mileage car might be unknown but your getting to the point where alot of stuff is going to start failing on american cars. I know they have gotten better but 100K was usually about the time they implode. If it were me I'd return it to stock and sell the parts, then the car, then get one you've always wanted modded the way you want, unless your already driving it.

As far as engines go, an MMR shortblock is way cheaper then what your looking at.

 

[Avispa]

Long overdue reply to this thread

Decided just to refresh the top end. 16 new exhaust guides, all new valve springs, three angle valve job, resurfaced the heads and put it all back together with Ford TTY head bolts and head gaskets. I let PSI performance in Kemah, TX do the assembly work :shrug: this'll get me kicked out of the DIY club, but there just wasn't time what with my work schedule. Anyway, it's back to 610 at the tires and burns drag radials in 1st gear just mashing the throttle. It all turned out great. Still goes 5000 miles between oil changes and doesn't use a drop of oil.

These motors really are a freak of nature.

Thanks again for the suggestions and advice.

...and Ponyracer, I had ZY convertible one of these things decked out like the one I have now. I really miss that car. My screen name is actually the Spanglish word for "bee" and it was on the license plates.

 

[hotcobra03]

Cool..you got it up and running again..

how much did it cost to have work done..

 

[GodStang]

You have a 03 cobra right if so and it's the stock block with rotating assembly it most certainly has forged piston made by mahle correct me if I'm wrong on the manufacturer. The rods will be h beam made by Manley and a Kellogg forged crank.

The pistons are the bad/weak spot on these motors. They are the first thing you should upgrade on these motors if going inside.

 

[Avispa]

Cool..you got it up and running again..

how much did it cost to have work done..

About 4200 for everything, parts included, even 2 gals of motorcraft gold antifreeze. Labor was about 2500.

 

[hotcobra03]

About 4200 for everything, parts included, even 2 gals of motorcraft gold antifreeze. Labor was about 2500.

Ouch..but you should be good for another 100k of fun..

Place that did work..did they pull engine to do work...

When I did mine while waiting on machine shop I took off oil pan.

glad I did..oil pump screen was 50% blocked from debris..silicone and timing chain guide plastic..

even junk in oil cooler tube

 

[Avispa]

They didn't pull the motor, but they did pull the pan. The bottom end was spotless. Nothing to do but bolt the pan back up.