2002 Mercruiser 5.0 EGR pipe

[GhostriderL76]

Is there any negative effects from removing the EGR pipe (right side exhaust Manifold to intake manifold)? This is a 2 bbl carb model. I know on many EGR vehicles removing it can actually hinder performance as the diluted intake charge allows more timing. Not sure if the thunderbolt 5 system would be effected, since it uses a single knock sensor for timing protection.

 

[alldodge]

I'm going to need a pic or at least the serial number of the block. The motor should not have a EGR but may have a PCV valve

 

[dubs283]

The motor should not have a EGR but may have a PCV valve

Some, albeit few mercruiser carbureted engines from late 90s to early 2000s were equipped with an egr system from the factory. This was for emissions/star rating for the epa based on number of units manufactured and how much pollutants mercury was "creating" by selling the product.

I've never fully investigated the operation of the system as far as troubleshooting and would guess abating the system would have little to no effect on engine performance or harm. Probably like abating and plugging on an automotive engine?

 

[Scott06]

Is there any negative effects from removing the EGR pipe (right side exhaust Manifold to intake manifold)? This is a 2 bbl carb model. I know on many EGR vehicles removing it can actually hinder performance as the diluted intake charge allows more timing. Not sure if the thunderbolt 5 system would be effected, since it uses a single knock sensor for timing protection.

When I repowered my 5.0 and upped to a aftermarket intake and edlebrock 1409 there is no provision for this and it works fine. I don’t think this is egr but rather heating like on a exhaust cross over on pre vortec engines


If you look at places like Michigan motorz who sells partial engines none of them use this provision.

 

[Fun Times]

That part is surly the hottest part of the whole engine under that shielding Yep, hand tested.

 

[GhostriderL76]

This makes the most sense, I assumed there would be a cross over in the classical sense but maybe not. Will look up an intake gasket set and see what the gasket looks like and if there are provisions for a crossover. I doubt it as this engine is essentially the Chevy TBI engine platform, which did not have crossover flow in the heads.

I think I will leave it as the intake probably needs the heat for proper carb operations. At 150* engine temps, that intake isn't very warm.

Thanks for the thoughts.

When I repowered my 5.0 and upped to a aftermarket intake and edlebrock 1409 there is no provision for this and it works fine. I don’t think this is egr but rather heating like on a exhaust cross over on pre vortec engines


If you look at places like Michigan motorz who sells partial engines none of them use this provision.

 

[Scott06]

I think I will leave it as the intake probably needs the heat for proper carb operations. At 150* engine temps, that intake isn't very warm.

Thanks for the thoughts.

Vortec heads do not have a cross over. I wasn't sure why you were asking- no reason to remove it. I blocked the cross over on a 65 GTO I have ended up taking it out as had trouble getting it to idle until it was really warm. Unless you are changing out to a 4 bbl leave it alone