Number 1 cylinder piston shot

[Madtown850]

So, I finally got the 97' Volvo 850 T-5 into my garage about a month ago and have started taking the engine out.  

Cylinder head is out and on the bench and to my dismay, I do not have a burnt valve, but rather a burnt piston. See pic:

I have read some of the rebuild threads and I am planning on taking apart the internals of the block, so this isn't catastrophic.  But, my question is:

In your experience (if you have had this one) should I be looking for a new block or is there a chance of rehoning for the rebuild?

Thanks

 

 

[Zappo]

Not enough information to properly answer your question, but as long as your cylinder bores are still good, the block is probably fine.

Do you know what caused that?  What did the spark plug look like?

I melted a piston and was able to reuse the block without boring over.

[Madtown850]

97' 855 T5

 

I turned the crank and lowered the piston to see if any damage occurred, the pic shows some melted metal adhered to the cylinder and the cylinder has slight imperfections that I can feel with a fingernail.

My intentions are to do several upgrades to the vehicle, including:

1. Manual Swap.

2. New 18T turbo

2.5. Connecting rod upgrade

3. Full Turbo back exhaust (which is the best value??) 

3.5.  What to upgrade on cylinder head ( which model/year has better or best flow?)

Exhaust Manifold upgrade (? Is this needed, if so which model/year has best flow?)

5. IPD sway Bars. Most other suspension has been replaced.

6. White injectors with higher FPregulator

7. All new silicone turbo and vacuum hoses.

8. 4.4 ECU tuning... 

 

Since I have the engine out, I am contemplating just replacing the following items:

a. Steering rack

b. power steering pump

c. Alternator

d. AC compressor.

e. radiator

f. all coolant hosing

g. oil cooling lines

h. trans cooling lines

 

So, my questions at this point would be: (Does any of the above not make sense to do?) and below:

1. At this point what would you do about the cylinder? rebore (bigger?) new block? other?

2. In a 400 HP world what would you do if you had things torn down this far, and what are the rough associated costs if you know them from experience?

 

Thanks guys and Merry Christmas!

 

 

I would like to answer the question of what caused the piston to burn on this Volvo 850 T5, but I can only guess:

I took the plugs out and tossed them prior to inspecting (stupid move) so I don't have any info or observations from them.

I have not experienced this happening yet on an engine so my guess may not be as good as yours.

Guess 3: Detonation event with things not properly tuned and engine not at stage 0

Guess 2: slight leak in piston rings at the point of damage to piston, causing an oil leak which caused predetonation/high temp and melting

Guess 1: Possible arcing event from spark plug to piston head?  I don't know if this is something that happens typically, but I do know electrical arcing would explain melted metal...(it would be nice to look at the plug as ZAppo asked.)

 

Thoughts?

Engine and components are out of car for repair:

 

[Zappo]

The spark plugs would tell you a lot.  Unlikely to be ring damage.

Take the block to a machine shop and have them check it.  Other than the aluminum deposit it seems okay.  If not, bore it .010 over.  You will need to replace the pistons in that case, but if you are looking at 400 hp, I would upgrade them as well as the rods.  Better to do it when everything is apart now then to upgrade later.

[Madtown850]

Thanks, I have everything apart and yes, it does just seem like aluminum deposit and no further damage. I plan to take to a shop for cleaning and inspection and to hone the cylinders.

I am looking into performance rods and pistons and would like to get a set of both purchased soon so I can put this back together.  What brands of rods and pistons are recommended for the 350-400HP range?

I found some Hbeam rods on maxpeedingrods.com that seemed to be a good price, otherwise Vivaperformance? 

How about the oil pump?  should this be changed out with a new OEM or can it be overhauled?  I have seen conflicting advice on this.  

Any other "must do's" when this engine is completely taken apart? 

 

[Zappo]

I would change the pump.  I am not sure if it can be overhauled or not.

Pretty much any H-beam rod will handle the power you are planning.

 

[Madtown850]

So, I got around to taking the pump apart since it was just two hex head bolts, when I took it apart there is only a gear, an impeller and a spring.  I figure I can just replace the spring, since the other two pieces looked perfect. (since the new oil pumps are $300+) In addition, I read some threads on this forum regarding replacement pumps that aren't as good as original and people going back to the higher mileage pumps because of premature pump failure.  I am still trying to figure out what exactly would fail in the replacement pumps( or the originals, other than the gaskets) since they are so simple in design.??? Does anyone know?

Since the engine is apart I think I will go with the Wiseco forged pistons and chinese rods.  The advice of the machine shop I am working with is that they will inspect the block and measure, and then when they give me the ok, I should pull the trigger on the pistons and rods and new bearings. Then they will bore when they have the actual pistons in hand, so that they can measure each piston and achieve better accuracy on the bore. 

Are these components overkill for 350-400? or is it worth it to do this now since everything is dismantled? (my number 1 piston is shot anyway..)

Also, after asking about pricing on doing the head, it ends up being about 350$, I was looking at the clearwater cylinder head company and wondering if it just makes sense to buy a fully remanufactured head from them vs. having the shop do it.

Is there anything that should be done to the head for this HP range? Ive read that it is good up to this HP, but thought I would double check.  Ive found several used s60 exhaust manifolds for reasonable prices, what about intake manifold?  Does anybody use the ipd heat break for the intake manifold? Is there any noticeable gain?

I have done my searching and reading, but sorry for all the questions.

Thanks