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Eddie, slight de-rail. My 500efi's just rolled over 600hrs unopened. They were not hard hours, would say 95% of the time at 3400rpm. What should I be looking out for? Should I pull the heads or do a leak down over the winter?

Quote:

Originally Posted by Young Performance (Post 4492947)

A big deciding factor is the year model of 525's. If they are pre 2007, they will have the old style headers, composite head gaskets and GM head bolts. You can tell which headers they are by looking at them. If the outer tube goes all the way to the flange where they mount to the cylinder heads, then they are the old style that are prone to leaking. if the outer tube stops short of the flange and is welded to the inner tuba bout 3/4" before the flange, then they are either the later style or replacement Gen X headers. Both of these are very dependable. The earlier ones must be watched closely. If not's if, but when they will leak. Sooner or later they will go. Replacement Gen X headers are about $5600 per set. So, plan on 11K if it has the old style headers. If you wait until they leak, there is a good chance you will trash the engine. We have rebuilt countless 525's because of that.

No matter what year engines they are, the valve springs will need to be changed NOW. They are too weak on the seat for the cam in that engine. They can cause numerous other issues if left alone. The engines will need to be pulled, heads removed, etc. You are looking at about $3500 per engine to pull them, tear the heads off, perform a valve job, surface the heads, replace the springs, retainers, locks, seals, head bolts and head gaskets, put them back together and put them back in the boat. We have done probably hundreds of them. If you use the search function, you can find some previous posts that I have made on the 525's. I've made numerous posts over the years detailing exactly what needs to be done to which models.

If you need any help, have any questions, etc. don't hesitate to give us a call. 615-216-7449
Eddie

Thanks, Eddie! Is your shop close to the Annapolis area?

Eddie's shop is in TN - however MDG is in Edgewater. Well respected shop.

Quote:

Originally Posted by dcb (Post 4493028)

MDG is in Edgewater. Well respected shop.

+1,

Quote:

Originally Posted by thirdchildhood (Post 4492957)

Your friend is right. I did valve springs at 400 hours. Leakdown was good. Valves looked good going through spark plug holes with remote camera. I probably didn't even need to do the springs. The 525 is a great package.

Just to clarify. Mine is an '08 vintage with the new style headers and Cometic head gaskets.

Quote:

Originally Posted by thirdchildhood (Post 4493032)

Just to clarify. Mine is an '08 vintage with the new style headers and Cometic head gaskets.

You were one of the lucky ones. There is a lot of evidence to support that the top ends of 525's should be refreshed sooner than that interval. My 525's are 2008 as well and I had rocker failures at 200 hours most likely caused by too light spring pressure. That rocker failure cost me the engine because the needle bearings made their way through the lifter valley and below. Tore up the crank and cam.

Me personally, I'd have the top ends done no matter what, just for peace of mind. I think the $3500 Eddie just quoted is well worth it to know that all the weak points are addressed and the motor has been opened up and looked at. Like said above^ a very small valvetrain problem can cause catastrophic results...

Quote:

Originally Posted by 370ss500efi (Post 4492970)

At a minimum, I would do the top ends. Perform a leak down first to see what you're working with. I've seen 500's with 450 hours that looked like death and I've seen them with 700 hours that looked fantastic. Didn't seem to have much to do with the way they were ran, which doesn't make a ton of sense. Both were well cared for as well. The 450 hour one was babied and the 700 hour one was flogged. Doesn't seem to matter much. I think upkeep and maintenance has more to do with it. We've seen the same things with 525's. We just did some with 500 hours and they were wore out. We've done others with more time that looked like they were new. I've seen at least 2 dozen that have broken connecting rod bolts.....all with less than 300 hours.

All and all, the 525 is a very good engine. They have continually changed things on them eveyr year. The later ones are far better then the 2003-2005 models. They addressed little issues each year, which ultimately made for a better engine. In 2008, they even upgraded the rod bolts from ARP 8740 bolts to ARP 2000 bolts, as the 8740 bolts have broken.
Eddie

Quote:

Originally Posted by 529 Program (Post 4492992)

Thanks, Eddie! Is your shop close to the Annapolis area?

Eddie is in Tennessee but worth the trip.

Padraig

My 500efi's had 345 hours on them when I blew apart a lifter,springs where weak and head gaskets where bad messed up the cam when it went and the roller and arms made it to the oil pan
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