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1G Cracked a piston? Choose my car's fate

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tudds2k

15+ Year Contributor
138
9
Aug 28, 2008
Long Island, New_York
Hello DSMTuners,
I've had this news for about 3 weeks and just verified myself what I've been told is a cracked piston(See attachment)
Some background on the car is that its an all original 100% stock 1990 GSX with all original panels(one side was painted many years ago). The trans grinds from 3-2 but otherwise drove fine. I had this weird buzzing noise over 4,000rpm and took it to a DSM shop for diagnosis. The car was fine driving there and was fine in the parking lot. Once the owner asked me to start it up, it sounded bad. Engine light was on. He said to come back for a compression test and not to drive the car anymore. The DSM shoot out was coming up and they were booked for 2 weeks. I changed the plugs and fuel filter and drove the car once to put air in the tires(it drove 100% fine then). My girlfriend drives it to the DSM shop and it was popping and shaking away. They did a compression test it and it was 165 in all 4 cylinders. They put a camera down the cylinder closest to the timing belt and said my piston is cracked. They will swap in any motor I bring them for 1200 bucks. They will install new timing components and a new clutch with that price. He recommended getting a JDM motor. so now I bought a walmart camera and checked myself. I have a few options and one of them includes burning the car to the ground

Cheapest
1. Buy a beat up body but running 91+ DSM and swap the motor/trans/transfer case/shifter cables myself Not sure what to do with CAS or other items that are different from 1990 to 1991+. I'm sort of confident I can do this myself before the winter spending a few week ends and having a friend come help. I wouldn't separate the engine from the trans for the removal or installation I'm guessing

Cheaper
2. Performance Part out has a rebuilt motor that hasn't been run in 3 years.
Complete rebuilt engine for DSM & GVR4. 6bolt 1G - wiseco forged +.020" pistons on stock rods. Balance shafts removed, stock rebuilt 1g head, MLS gasket, 2g lifters, stock cams.
165/145/165/165 compression tested
Have this installed professionally with a new clutch/timing belt and swap the trans/transfer case/shifter/cables

Oh God Why...
3. Have a short block built by a reputable vendor. Have them install it. Buy trans and accessories from above or just rebuild the trans. Have a fresh motor and trans for future upgrades next Spring. I can't find a vendor who will build and install this. I can hardly find anyone to answer my emails. I do not trust myself to install all the engine accessories like the front case and oil pump. I'm certain I can remove my head and install it on the new engine.

4. Buy another car and leave this current one in storage($50 a month) next to my fox body mustang that I never did anything with because my girlfriend doesn't like it.
I found one that seems ok for $4,000 and I was going to offer $2500 and go from there

The goals are to be a fun reliable cruiser for my girlfriend(/wife in training) and I that runs 12s but everyone always wants more....

I have 3500 cash from selling my LS1 Procharger kit and thats like found money to me. Spending a bit over that is fine but I'm not looking to spend $2,000 on a trans.

Thank you all for your input. I really appreciate it.
 

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They did a compression test it and it was 165 in all 4 cylinders. They put a camera down the cylinder closest to the timing belt and said my piston is cracked. They will swap in any motor I bring them for 1200 bucks.

Hold up...

There's no way in hell you'd get 165 across the board on a compression test with a crack damn near all the way across the piston face. Those are healthy motor numbers. Additionally, the "crack" in the piston looks raised (could be the crappy ass pic though). No crack I've ever seen looks raised like that.

You may want to choose option 5: reconfirm the diagnosis. A leakdown test would confirm a cracked piston. If the piston is cracked, you should have air $hitting into the crankcase, out of the dipstick tube, etc.

You could be mistaking carbon buildup for a crack, especially if your camera isn't very high resolution:
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They said that it heats up and the crack expands. I saw them do the test. They used a faulty gauge at first and he said I bent all my valves.
The car runs fine for 10 minutes or so. I asked for them to swap a coil and they said it's their job to diagnose it. They checked with the camera(snap on)
I have more pics but it says they are too large. I looked at another piston for comparison.
 

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I will take better pics tomorrow and rent/buy a better camera if I have to.
 
They said that it heats up and the crack expands. I saw them do the test. They used a faulty gauge at first and he said I bent all my valves.
The car runs fine for 10 minutes or so. I asked for them to swap a coil and they said it's their job to diagnose it. They checked with the camera(snap on)
I have more pics but it says they are too large. I looked at another piston for comparison.


Find another mechanic.


Faulty compression gauge, then bent valves, then expanding piston cracks? Not buying it. Nothing in those pictures looks like a crack to me, although those pics don't really show much detail, IMO.

A cracked piston (especially one with a crack that large) will leak compression. Let's say your mechanic isn't full of $hit, and we believe what he says about expanding piston cracks. He should be able to do a compression test cold, and show 165 across the board. Then, he should run the car and do a compression test hot. If his theory is correct, compression on the cylinder with the cracked piston would be significantly lower with the car hot. Mystery solved. Any decent mechanic should be able to come to this conclusion. Additionally, if ALL your valves are bent, you get zero compression on ALL cylinders. This isn't rocket science here. Sounds to me like they are idiots, guessing at possible problems, and have an overwhelming willingness to swipe you credit card.

I'd stop wasting my time with a camera. There are better and easier ways to diagnose issues like this. Like I said, a leakdown test would easily confirm any of the issues your mechanic is saying you have. Bent valves, cracked piston...All easily identified via a leakdown test. A good mechanic would have told you this...Instead of anal probing your cylinder bore.
 
Listen to this guy on this. You are getting duped.

I would think with a cracked piston while driving you'd be blowing oil out every seal from the pressure...


$1200 for a motor swap? Man I need to charge way more. That seems excessive even for a certified shop. These things are not that hard to swap. Oh I guess with good timing belt and clutch components thats not too bad...

My suggestion is do as much work as you can yourself.

If I really wanted to know I'd pull the head off in car and clean that piston up. If its good have the head surfaced and valve job and slap it back in with new timing components/gaskets.

But I can pull these off in a few hrs too... If that, I think my record is a vw 2.0 head I had off in 45 mins.
 
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I agree with gst with psi. There is a lot of mechanics out there but most of them just want your money. Try to do some test on your own. Do a compression test when hot and cold.
 
Since you are asking what you should do IMO sell the foxbody and buy a daily if you don't already have one. Keep the DSM and learn to work on it and slowly make progress to get into the 12's. Oh and listen to everything GST with PSI said.
 
I will do a compression test hot and cold. I was very hesitant about hearing my motor was a dud. I know no one wants to believe that but I was a little weird about it. I was offered a "heavy discount" if I let him keep my old motor when he swaps them.
There aren't many other dsm shops around here. I was willing to drive 4-6 hours away to have the car done right.

this is not my daily. I'm a recovering car hoarder.
 
Im with the rest, It doesn't look like a cracked piston to me.

If it was cracked, and that long and that wide, that side of the piston would have moved and/or fell down the bore.

Rings would have busted, the cylinder bore been in shambles.

Compression would be down, cold or hot, blue smoke out the tail pipe.

Now could you have cracked a ringland ? possible, not probable tho.

165 compression across the board? I can not remember the last time I saw a perfect test like that, more so on a stock high mileage engine, there is always some sort of variance, due to casting flaws of the combustion chamber, piston recession, machining tolerance.
 
Sounds alot, like some one sees the opportunity to benefit from your current level of experience. Please don't become " another one ". In the countless scams perpetrated by mechanics. It's super simple taking a look at an intro to physics book, you will quickly find that it's near impossible for a piston to compress gaseous mixture with a crack or chip or ..................... Take the advice from these nice guys willing to help. And DSM the f**k UP!! Good luck.
 
And you said the check engine light was on when your car was "shaking", so obviously, and you need to do is hook her up to a logger to see whats at fault- loose injector plug, cas plug, igniter plug would all do this and throw a check engine light and leave a readable code for each.
 
Thank you guys. I will look into this more. I've been heart broken over this.

The engine light didn't stay on after the next drive. Does the paper clip trick work for these cars to read the codes ?

I'm so excited there is hope that my car is not dead.
 
Just run to the part store and pick up a compression tester, sounds more like you have 1 or 2 dead cylinders not firing. If you find out the motors fine I would take the rest of the money and get the transmission rebuilt. And you would still have more left for some upgrades and maintenance.
 
I will do a compression test hot and cold. I was very hesitant about hearing my motor was a dud. I know no one wants to believe that but I was a little weird about it. I was offered a "heavy discount" if I let him keep my old motor when he swaps them.
There aren't many other dsm shops around here. I was willing to drive 4-6 hours away to have the car done right.

this is not my daily. I'm a recovering car hoarder.

Probably because he wants your bullet proof six bolt and will swap in a 7bolt block...
 
I will do a compression test hot and cold. I was very hesitant about hearing my motor was a dud. I know no one wants to believe that but I was a little weird about it. I was offered a "heavy discount" if I let him keep my old motor when he swaps them.
There aren't many other dsm shops around here. I was willing to drive 4-6 hours away to have the car done right.

What DSM shop is that? You should let everyone know, so nobody goes there ever again. Heavy discount to keep your old motor? W T F? If you motor was trashed, there wouldn't be any incentive for them to keep it. See where this is going?

Drive your car to my house, I'll do it right. Just leave your credit card when you go :sneaky:
 
I wish it was that easy. I can't find someone to take my money.
He said he could sell the head. I pray it's just a wrong diagnosis and he was trying to actually help me. Once they stuck the camera down there we looked for 15 seconds and they put the car together. He had a machine shop in the shop and a ton of 1gs in a yard with blown motors

i will post the name when I actually figure out if it's dead or not
Will the ses light say if it's an igniter plug?
 
Ok so you saw a bunch of cars in his yard, And I guess he told you they all had blown engines, odds are most just had blown HG that is the most common issue with the 6 bolt. Followed by spun rod bearings... in the loosest sense of the word they were blown.

As for equipment, what all did he have in his machine shop? How old? what shape was it in?

Do you have some basic hand tools? A bit of work space? Why do you not pull the head? Then you will know if the short block or piston is junked.
 
The error code will state if there is a problem with the ignitor or a fuel injector or maf. The check engine light absolutely WILL NOT come on if you have a cracked piston or other mechanical fault in a 1G, it doesnt look for that. This is going to be the cam angle sensor, ignitor, coil pack or a fuel injector plug is dicked up, end of story, please do not let this place butcher a perfectly good car and motor, man. Check the plugs on your fuel injectors and the CAS and coil and ignitor and try to find someone close enough to help you plug a logger into your car.
 
What kind of logger should I buy ? I plan on getting ecm link
 
I'm looking to get ecm link in the spring. Can I jump the terminals with a paper clip to make the ses light flash?
 
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