well as some of you know I have been replacing the headgaskets and the timing components. Followed all the directions online but on one points I made an assumption. The new crank gear had to timing marks on it. I assumed one is for the driver side and one for the passenger side. That is not the case. I didn't know, not did any instructions I came across mentions to only use the front mark. Either way it's my fault for assuming and not double checking.

put it all together and tried to start. instantly heard two loud clanks and motor locked up. tore the driver side head off as the rear gear was off on timing based on the fact you should only use the one mark in front. took the heard of and well...you can see the pics below!!.

Question I have is this:
Can I still use the pistons? Obviously i'm replacing the valves. I've read several posts on other forums saying your fine to use. Then some that say yes you can use them as long as you take a dremel and smooth things our as much as possible. Then other say "NO" as it will get hot and cause detonation.

The truck is 4x4 and pulling the motor or dropping the pan really isn't an options and sinking more money into it at this point I'm not sure is worth it. It's not a race truck, just a daily driver.

on a side note...if I used the pistons I should probably stop using the Edge tuner or am I able to mess with the timing/setting to keep things cooler in there?

Thanks for any suggestions. I'm mainly looking for responses for those that have tore into engines and might have used pistons with scaring.

 

After removing the head I put the chain on crank and passenger cam and rotated the crank...everything rotated smoothly. Driver head looked good and so did the guides. The valves obviously need replaced. The cylinder walls looked good with no scaring.

 

Midnight,

Wow man! Sorry to hear about your difficulties!

It's difficult to judge without seeing the pistons in person but I don't think I'd attempt to use those damaged pistons. If they came apart, it would probably be catastrophic for the engine. Also the dents and rough edge could easily create a hot spot and cause pre-ignition which would cause emissions problems and possibly additional damage.

What do new pistons and rings costs and how many pistons are damaged?

As to whether to repair or not, you probably don't have much choice at this point. Your truck is probably worth little or nothing in it's present condition so at this point, it's a choice of fix this engine, buy a rebuilt one or buy used one and keep your fingers crossed.

 

Thanks for the reply!

If I used the pistons in it now I had planned to take the rough edges down with a dremel/air grinder. Any high points or edges coming off where there is a dent.

The damage itself was caused by the starter. the truck never started and ran. As soon as the starter engaged and turned the drank the valves smacked the pistons. From a few other sites I've posted on, along with a few others I've talked to on the phone mention that the chances of a piston cracking at that stage is minimal (just from the starter vs actually running etc..).

I would love to put another engine in or rebuild this one..but by the time all the money is put into it..it wouldn't be worth it. There are other things like the tranny, transfercase, other components etc...that could go at any point as well being it's a 99 and has 197k miles. Not sure what route I'm going with yet.

 

Scrap yard engine in Columbus OH for $475.00. Have a look on http://car-part.com Use 5.4 vin code L for the engine. If it were me that is what I would do. Actually I have done this in the past...

 

It is also possible that the rod(s) bent when the pistons hit the valves.

 

On a 200k engine, I'd reuse those pistons. I would NOT use a dremel to smooth the edges, but I'd use a brass wire wheel to round the sharp edges as it will remove less material and create less "dust" in the cylinders.

I had an Expedition with a 5.4 that consumed a helicoil and marred the top of a piston badly. In the heat of summer all loaded up with 87 octane I had no pinging issues.

This is what I would do as I have a lot of mechanical experience and I know how to prep a block and head for MLS gaskets. You may want to consider JMC's advice on getting a used engine though. No, swapping the engine is not fun and some of those transmission bolts are a pain. I use a mile of extensions to get to them and some are invisible. With the intake already off, you're 1/3 of the way there. I was able to sell my knocking 5.4 for $350 on craigslist.

Post up some pics of your head prep and I can probably tell you if it will seal.

 

Thanks for the replies. When you say brass wire wheels, are you saying the ones you attach to a drill vs the dremel/grinder? I was planning to have a shop vac next to what ever area I'm working on to collect as much as possible.

I ordered the new valves and hope to install everything this weekend.

If there are cracks in the piston or rod damage is that something I would notice right away or could be months down the road before I notice anything. Just curious.
I usually run 93octace as I've ran the edge tuner for the last couple of hears on the tune 3....so I'm used to putting 93 in there will continue too. Not sure if that will help things or not if there are high points that get hot.

 

I guess you could use the wire wheel in Dremel if you prefer, but I don't know if it would have enough power.

I'm confident you don't have a bent rod or cracked piston. If you do, you'll know right away. It is possible that you increased the clearance in the rod bearings since it happened while cranking and there was no oil pressure yet. If so, you'll have low oil pressure or a knock.

When you replace the valves, you should at least do a hand lapping. You can set the head on its side and put liquid in the ports to see if the valves are sealing.

Please post up pictures of the head and block prep for the MLS gaskets.

 

Wow.