Mercruiser 1.7 Diesel - Replacment Pistons

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Hi all,
We have a 6.5m RIB with the Mercruiser 1.7 diesel. It is the older generation (Not starting with 88).

We knew that a piston (#3, as always!) was going to eventually crack, and it did.

We have the engine apart. The pistons are the old Isuzu pistons with the only marking on it being: B 3770

Does anyone know where we can source 4 x new pistons? We know these early pistons were not up to standard and they were uprated. We just want to ensure we are getting the correct pistons.

My partner in this boat is a mechanic so quite lucky. He reckons it wasn't fuel that caused the crack, but we're getting the injectors serviced for good measure. We reckon it was heat and potentially over-propping that caused it... we have replaced with a lower pitch prop (engine can now rev to 4400, but we never go above 3600RPM) and the heat exchanger was clogged (now cleared... boat is now only in fresh water use).

Cheers!

 

[spannerman]

Check the wastegate moves freely, the shaft with the operating arm rusts where it goes into the wastegate housing. This causes overboost as the wastegate can’t open and has been the death of many a 1.7. Its a service item to lube these and the spring in the pressure capsule is very strong so it takes a bit of effort to move the arm.

 

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Check the wastegate moves freely, the shaft with the operating arm rusts where it goes into the wastegate housing. This causes overboost as the wastegate can’t open and has been the death of many a 1.7. Its a service item to lube these and the spring in the pressure capsule is very strong so it takes a bit of effort to move the arm.

Yup, well aware of that (this is my 2nd 1.7) but thanks for the info!!

 

[rafiki_]

Hi all,
We have a 6.5m RIB with the Mercruiser 1.7 diesel. It is the older generation (Not starting with 88).

We knew that a piston (#3, as always!) was going to eventually crack, and it did.

We have the engine apart. The pistons are the old Isuzu pistons with the only marking on it being: B 3770

Does anyone know where we can source 4 x new pistons? We know these early pistons were not up to standard and they were uprated. We just want to ensure we are getting the correct pistons.

My partner in this boat is a mechanic so quite lucky. He reckons it wasn't fuel that caused the crack, but we're getting the injectors serviced for good measure. We reckon it was heat and potentially over-propping that caused it... we have replaced with a lower pitch prop (engine can now rev to 4400, but we never go above 3600RPM) and the heat exchanger was clogged (now cleared... boat is now only in fresh water use).

Cheers!

Go to your Vauxhall dealer. These engines were extensively used in Astras

 

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Go to your Vauxhall dealer. These engines were extensively used in Astras

The pistons were uprated though, that's what we're after. I think (could be wrong) that the original pistons just weren't up to the task of the higher HP.

 

[rafiki_]

The pistons were uprated though, that's what we're after. I think (could be wrong) that the original pistons just weren't up to the task of the higher HP.

Can you see the markings on the pistons that aren’t broken? Worth quoting these to the Vauxhall parts dept?

 

[Davy_S]

The Piston Guy: The Best Place To Buy Aftermarket Pistons

 

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The OE pistons that came out are ISUZU B 3771

There are now 3 grades available: A / B / C

The Isuzu block is a 4EE2

I've been told that i'm after Grade B, which makes sense. I found a part no. but apparently Mercruiser don't source (We know they don't make them) the uprated pistons anymore, so back to the drawing board.

People seem to state that good quality aftermarket (car) pistons for the 1.7 car engine are better than the OE Isuzu pistons.

Just need to find which aftermarket pistons to get!