Block-guard?

[Michael211_2000]

Is a block-guard useful if your SeaDoo 4-TEC isn't setup for racing, but is essentially stock (215 hp SC'd w/R&D intake grate) and just used for casual fun at the lake?

Thanks.

- Michael

 

[Dr Honda]

Do you mean an engine Girdle?

Actually, I don't like them in any application. The problem is... the aluminum of the girdle will expand differently than the engine block, and it can actually push the cyl, and break the head gasket seal. Also, they are known to warp the cyl, and cause them to become out of round.

This has been the topic of many of the "Import" tuners for years. The only real way to do it is to have them welded in place, and the block re-machined. Any of the drop in girdles will cause more issues than they prevent.

 

[Spade88]

They are actually in fact refered to as block guards. They are actually beneficial in high boost applications, in keeping the cylinders from expanding.
Also they can assist in keeping the cylinders from walking under high RPM load in boats with aftermarket ecu's/higher rev limits.

As far as a realistic benefit in a stock rec boat, yes and no. Only real pro that I can see is, it MIGHT aid in the preservation of the cylinder if the boat drops a valve. The 4 tecs, especially pre 06 are infamous for dropping exhaust vales. Usually when this happens, it chews the head, piston and splits the cylinder all the way through the block. So it's up to you.

Here's an example of an 05 I had..see the crack ? A block guard arguably could have prevented the block from becoming a pile of scrap. (It's prolly a budwieser can now)

 

[Dr Honda]

That engine dropped a valve, and it would have been trashed regardless. That damage had NOTHING to do with a cyl that walked.


As far as what they are being called... whatever. We can call them block guards.

 

[Spade88]

That engine dropped a valve, and it would have been trashed regardless. That damage had NOTHING to do with a cyl that walked.


As far as what they are being called... whatever. We can call them block guards.

Read my post carefully and tell me where I said that damage came from a walking cylinder....never said that. I said that damage came specifically from a dropped valve...9 times out of ten, when these motors drop a valve it blows out (cracks) the cylinder wall all the way through the block.. It is ''theorized'' by a few tuners, that in the event the motor drops a valve (happens more often than not on a 4 tec) that the block gaurd can potentially save the cylinder...that's all I said, period. I have personally witnessed a few motors live on after dropping a valve with a block guard.

You layed out some cons to a block guard, I simply layed out a few pro's.

 

[Michael211_2000]

Replacing the sodium filled exhaust valves with the newer solid exhaust valves seems like a better solution than adding in a block-guard thingy. Better to not drop a valve to begin with, wouldn't you think?

That is 1 seriously banged-up piston in your pics, Spade! Ouchie! The engine can actually keep running after a valve head pops off? I'd have thought it would lock-up it's cylinder and kill the engine instantly!

Final question regarding valves... is a "dropped valve" the same thing as having a valve's head break off, or is a "dropped valve" another condition in which the entire valve fails to get pulled close (such as the spring on the valve failing completely or losing it's tension)? I've always wondered just what a "dropped valve" is. (Thankfully, I've never experienced one... and hope to never experience one!)

Thanks ya'll! Trees are starting to bud out here in South-East Texas, Spring must be just around the corner... as soon as I'm pretty positive we won't get any more freezes, I'm going to flush out my RXT's lines (to get the antifreeze I pumped in there out) and start getting it lake-ready again! Can't wait!

- Michael