worf928

Enzo:

https://rennlist.com/forums/showthre...highlight=lean

Tass 928

The Answer !!

I pulled the t-belt so I could rotate the cam by hand. Then I pulled an intake runner so I could see the back side of the intake valve. As soon as I had the runner off the problem was obvious. The intake port was contaminated with glass bead. My fault.. I didn't do a very good job cleaning out the plenum and runners after they were glass beaded. I washed them but there must have been a pocket of bead material somewhere in the plenum.

So..I can actually see the beads holding the valve open. Introduce air into the bore and add carb cleaner behind the valve, it blows bubbles. I was able to wash that valve with carb cleaner and get it to seal. Unfortunatly I cant' reach the exhaust valves but my leakdown tester tells me they are leaking. I need to wash this material out of there. I have been told that water won't do any harm.
I am thinking of making a hose fitting for the sparkplug hole and a bolt on flange/fitting for the intake port. I'll unbolt my exhaust from the headers and then just flood the cylinder while opening and closing the valves to wash everything out. I may add some compressed air to the water line to agitate and scrub better.

What do you think? Am I nuts? Just tear the motor down do it the "right" way?

Dennis Wilson

Dave,

The exhaust valves are prone to burn in this situation so my suggestion is to pull the heads and have them checked by a good machine shop.

I was hoping it would be something simple (and cheap).

Dennis

hacker-pschorr

Mark, no offense but it's obvious your experience with boosted motors is well, zero.

Lean air/fuel is not the only way to detonate a motor. Too much timing + boost (toss in high compression from all the carbon) can (and usually does) cause detonation. Just the timing + boost alone is how many boosted motors are destroyed.
I've seen motors running 10:1 detonate on the dyno, it's NOT the only factor.

To say being "real lean" on a boosted motor would cool the charge........please stop giving advice like this. I'm not saying the "theory" is false, it's not good advice.

Based on Tass's last post it looks like detonation was not the issue, just needed to clarify a few things.

/it's early, I'm the only one on my team working today so yea, I'm crabby. Please tell me someone else will be tuning your new motor.

Tass 928

In light of my very short run time ( 5 minutes or so) do you think I may have been spared the burnt valves ? I am thinking of tryng the wash-out technigue on one cyl to see if I can get it to pass a leakdown test. What do you think of the idea of washing with water?

cold_beer839

Would some of those beads get down around the piston rings and damage the cylinder walls?

I would say pull the heads and really clean everything good. That's the only way to be sure.

It will cost you more time, but less money if the beads start to do damage after the engine is running again.

918-S

Because of the pressure of the valves on the seats, it's likely you crushed the glass beads into the seats. You will not be able to get the seats and valve clean by trying to wash them with water. Then it's very likely you have glass bead material in the rings now. In my opinion you need to do a tear down. Glass beads in your piston rings sliding up and down are a death sentence. The cylinder temps won't be high enough to melt the beads.

I built a franken engine for my BMW 2002 which involved notching the pistons for clearance, I made a cutter out of a valve and used an old cylinder head as a guide. I cut the pistons in the engine. I thought I got all the aluminum shavings out. As soon as I started the engine a small aluminum chip was blown into the exhaust valve and was pinched in the seat. I pull the head and was able to lap the valve to clean the aluminum off the seat. I doubt you'll get by with a water wash.

Stan.Shaw@Excell.Net

I don't expect YOU will be satisfied without pulling the motor apart. If you want to stay with a 4.5 or 4.7, see what is out there right now. Could be a low mileage well maintained motor out there that can't be sold. You might pick it up for a song and spend your time doing the motor R&R instead of possibly expending it on a lost cause.

I have an engine hoist and would find time to give you a hand... Probably bring in plenty of local help as well. Many would appreciate the opportunity to help you, as you have been quite the local event host

AO

Engine Pull Party!

hacker-pschorr

+1

Is this a stock 79 engine? If so that is the good news since it's not like you wrecked a set of EuroS heads.

I guess this is why a few engine builders I know will never bead (or sand) blast heads.

Hopefully the cylinders are ok, I fear as 918 pointed out, glass bead material scraping up and down the cylinder wall is not a good thing.
Look at the bright side, since that motor had so much carbon buildup, in the long run you will come out way ahead with a clean combustion chamber.

Not to be confused with the famous "Andrew Olson peter pulling contest".

SMTCapeCod

someone's been trying to seel Euro heads on here for a while....Fabio, maybe?
Probably hafta send em out for port and polish, there's a few months...Paeco?
j/k

SMTCapeCod

wow...high end ownership takes it's toll, but it's a '70- must be first prototype ever?
Just kidding. too bad BIN is still too high for eng trans and headlights, even if they were in good cond.
http://cgi.ebay.com/ebaymotors/Porsc...spagenameZWDVW

I especially like the bleeding fuel pump and ill fitting hatch.

Tass 928

I have a lot of effort into this car so I don't want to finish it off with a questionable engine ( glass bead contaminated= questionable). I am going to talk to Carl and see what options are compatible with my supercharger set up.

Maybe a complete rebuild or maybe just buy something else. If I have to do a complete rebuild I might as well keep the engine I have. It was running very well and has only 100K on it.

Thoughts?

AO

I think it's too early to say what you can do. You need to pull it apart and see if there is any permanent damage. If it's damaged, then assess your options.

hacker-pschorr

The biggest issue I see is the rebuild cost of a 4.5 liter.
From 928 International, 4.5 liter rings:
78-79 = $616
80-82 = $1,080
I'm not sure what the difference are so I posted both.

When I discovered this (and I own two 4.5 cars) I bought up the frist two 4.7's that came across my path that were a good deal.
4.7 liter rings = $250

So if you can find a 4.7 liter shortblock for $300-$400 or less (they are out there) IMO you are better off going that route.

For a boosted track car a 5 liter motor is the way to go since the pistons are stronger & you can run 951 rings. That adds a bit to the budget though.