Determining the Correct 3.0L Exhaust Manifold - Performance Product Technologies

Quickly and easily find the marine parts you are looking for by selecting the manufacturers catalog and searching by part number.

Blog RSS Link

Marine Engines Repower – Bayliner Cierra 2655, 1991 model Mercruser MCM 5.0l LX
Dennis, Thanks for your inquiry and the opportunity at earning your business. Since Mercruiser made both Alpha and Bravo sterndrive models with that engine I would not be able to tell you without knowing which one your engine is setup for. Can you give me the original engine serial number? Or can you tell me if [...]

4.3L Marine Engine Longblock Performance Specification
Mike, Thanks for your inquiry and the opportunity at earning your business. The Hp rating for longblocks is determined by the fuel system that’s install back onto the engine. For example since GM only produced one marine version of the 4.3L during this timeframe Mercruiser used this same longblock on their 190 Hp 2 barrel carb [...]

Marine Engines – Replacement marine engine for my boat 5.7 mercruiser 1992 #0d763634
Marty, Thanks for your inquiry and the opportunity at earning your business. Using the links below you can review your options. Let me know if you need any further technical information or help placing your order. In either case I will be glad to assist! Link to Block Code/Serial Number Location http://www.perfprotech.com/store/app_themes/PPT/images/block-casting-no.jpg Link to Remanufactured Longblocks http://tinyurl.com/68kcet8 Link to Remanufacturing [...]

Suzuki Marine Outboard Motors – Replacing a Fuel Pump on a DF70
Step by Step Video Instructions illustrating how to change an electric fuel pump on a Suzuki DF70 outboard motor. Watch Video

Boat Trailer Parts and Accessories – How to Replace a Boat Trailer Hub
Step by Step video instructions illustrating how to replace a leaky oil filled hub on a boat trailer. Watch Video

Performance Product Technologies Question & Answer Forum

Topic: Mercruiser 3.0L Exhaust Systems

Question: I need to replace my Mercruiser 3.0L marine exhaust manifold but cannot seem to locate the same matching part number. Why can't I find the same replacement "cast iron" exhaust manifold part number for my Mercruiser 3.0L marine engine?

Response: Mercruiser has made numerous changes to the 3.0L exhaust manifolds over the past 15 years. This has been due to a variety of reasons including GM dropping to large port cylinder head that the 120 Hp marine engines were equipped with. The original 42673 and 99798 series manifolds used back in the 1980's were replaced by the 806867 series manifolds in the mid 1990's which has most recently been replaced by the 860235 series manifolds. Today Mercruiser only offers the 860235 series manifolds in two different versions to replace these older manifolds. The new 860235 version manifolds from Mercruiser DO NOT have the removeable end caps with gaskets but they are the correct intended replacement part. Note that these currently available 860235 series manifolds only work for the engines using the large bore Mercarb carburetor. Mercruiser no longer offers a replacement manifold for anything using the small bore "rochester" style carburetors that required different mounting pattern dimensions. Also note that the exhaust manifold ports don't match perfectly for the older style large port cylinder heads however the manifold/head gasket compensates for this and will seal it properly. Let us know if you need any further assistance we will be glad to assist!

Part Diagram - 860235A03 (Manifold w/o Bosses) (link to part diagram)

Carburetor mounting bolt pattern is 3.69" x 2.00". There ARE divider walls between the intake ports on this manifold. The A03 DOES NOT have the additional bosses located on the outboard side that were used for mounting the shift linkage components. The Intake/Exhaust ports, Carburetor mounting, and Exhaust outlet are all the same on both the A03 and A04 manifolds.

Part Diagram - 860235A04 (Manifold w/ Bosses) (link to part diagram)

Carburetor mounting bolt pattern is 3.69" x 2.00". There ARE divider walls between the intake ports on this manifold. The A04 DOES have the additional bosses located on the outboard side that were used for mounting the shift linkage components. The Intake/Exhaust ports, Carburetor mounting, and Exhaust outlet are all the same on both the A03 and A04 manifolds (see picture below).

The 860235A03 replaces this 806867A 3, A 9, and A12 manifold shown below that DID NOT have the additional mounting bosses on the outside.

Mercruiser 30L Exhaust Manifold

The 860235A04 replaces this 42673, 99798, 806867A 2 and A 8 series manifold shown below that DID have the additional mounting bosses on the outside that were required for mounting the shift hardware.

Mercruiser Old 30L Exhaust Manifold

Technical Articles

Performance Product Technologies Question & Answer Forum