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OMC exhaust manifolds-risers problems

GLM Marine Products aftermarket parts come with 3 year warranty, stop engine overheating problems

  • Engine over heating problems
  • Water flow testing time
  • Year and horsepower exploded view drawings
  • Please see the GLM Marine for newest manifold conversions on older units not listed here.

By author Trish Dougherty

OMC engine manifold failures and heating problems can sometimes be traced to exhaust systems, however before unit is replaced check the water pump flow to the engine. Test is done by testing the time to fill a 2 gallon container at idle speed of 550 rpm to 650 rpm. 50 to 60 seconds for 400-800 stringer series boat years 1968 to 1986. Test time that our mechanics use, note the water pressure should be steady with little or no bubbles. Intermediate housing to water pressure line is one of three lines that need to be checked this way. To ensure water pump flow, clean or replace every 300 to 400 hrs.

51490 front view

51490 front view

GLM uses more advanced techniques for manifold casting their cooling systems versus other brands including OEM. The lost foam casting process provides greater control over the accuracy of wall thickness of the casting - which is vital in preventing thin spots that could possibly corrode through the walls causing manifold leaks.

This casting process provides longer lasting corrosion protection especially in salt water where corrosion happens at an accelerated rate. The lost foam casting process uses precisely molded foam pieces to excellent dimensional tolerances which are molded together for a highly accurate casting. The casting model uses an insoluble solution. Sand is poured into the foam mold after drying until every passageway and surrounding walls are completely covered. Molten iron is poured into the model which in turns vaporizes and takes the place of the foam piece. The sand is removed after the casting has hardened.

51330 Exhaust riser elbow

51330 Exhaust riser elbow

The final product is inspected and machined if needed. All GLM Marine aftermarket cast iron exhaust cooling system products are covered by a 3 year parts and labor warranty. Note 2 years for aluminum manifold or risers. GLM has an up to date web page for availability for certain items. If you do not see your item listed below, please view the GLM list on the manufacturers website.

 Click image below for individual parts

Exhaust manifold
pressure test

51490 back view

51490 back view

51490 right side
P/N 51490 Port or starboard side models 5.0, 5.8 and 5.8 liter.
351 OMC King Cobra E.F.I. Ford 302 and 351 C.I.D. with V8 engine.
Years 1991 and after 3852347. $288.29

Ford manifold parts 1991 and up

Ford manifold parts 1991 and up

P/N 51490 V8 Manifold kit for port or starboard sides with 5.0, 5.8 and 5.8 liter
1991 and up for 351 King Cobra E.F.I.
Ford 302 and 351 C.I.D. engine.

Including:
P/N 33790 (units of 2) 3852455
P/N 33810 Gasket 3850496
P/N 22486 Studs 2 units 3853434
P/N 21248 Nut (5 units) 3853404
P/N 21754 Screw 3853155
P/N 22290 Cap 4 units 3852476
P/N 01071 Clamp 3852602

May be required but no included:

P/N 51330
Riser 1988-1996 with carburetors 3857944

P/N 51332
Riser port side engine 1993-1996
with E.F.I. 3855271.

P/N 51334
Riser starboard side 1993-1996
with E.F.I. 3855269

P/N 01090 hose clamp 3852604

51330 Exhaust elbow assembly

51330 Exhaust elbow assembly

P/N 51330

Riser / elbow assembly for both side of engine.
Years 1988 to 1996 with carburetor OEM 3857944. $218.95
Includes
P/N 33810 Elbow gasket only 1 unit OEM 3850496

51332 Riser elbow assembly

51332 Riser elbow assembly

P/N 51332

Riser / elbow assembly for port side engine.
Years 1993 to 1996 with E.F.I. OEM 3855271. $209.09

Includes
P/N 33810 Elbow gasket only 1 unit OEM 3850496

51334 Elbow

51334 Riser elbow assembly

P/N 51334
Riser / elbow assembly for starboard side engine.
Years 1993 to 1996 with E.F.I. OEM 3855269. $209.09

Includes
P/N 33810 Elbow gasket only 1 unit OEM 3850496

33790 Exhaust manifold gaskets

33790 Exhaust manifold gaskets

P/N 33790 Exhaust gaskets set are sold in units of 2 OEM 3852455 $11.00

140 GM 181 4 cyl.

140 GM 181 4 cyl

Coming soon

P/N 51442 Model 140 GM 181 CID 3.0 liter 4 cylinder 1973 to 1990 assembly with cap and fitting.

800 Cobra gm 305-350 CID V8 1979-1989

51410 Exhaust manifold

51410 Exhaust manifold for starboard side OEM 912441

51420 Aftermarket OMC manifold

51420 Aftermarket OMC manifold for port side

800 Cobra gm 305-350 cid V8 1979-1989
P/N 51410 / P/N 51420 V8 GM 305 / 350 CID V8 CID V8 small block years 1979 to 1989 for both port and starboard sides.

Including:
51410 Starboard side 912441
51420 Port side 912442
31100 Gasket 3852468
33810 Gasket (1 unit) 3850496
22280 Cap (1 unit)909830
21791 Clamp 909830

May be required but not included:

22487 Stud 3852467 $8.98 2 (units)
21248 Nut 908700 $4.98 (5 units)
21493 Lock washer 309336 $9.98 (10 units)
51320 Riser / Elbow Assembly 909863
21896 Plug 315713 $7.98 2 (units)
21753 Screw 306435 $4.98 2 (units)
21496 Lock washer 306325 $4.98 2 (units)
89220 Hose (Cobra) 912374
89230 Hose (Cobra) 3852742 $21.98
01090 Clamp 3852604
01200 Clamp 984387
50730 Tube-starboard side (Stringer) 909609
50740 Tube-port side (Stringer) 909610
89221 Hose 909232
89223 Hose 909371
51430 OMC Manifold

51430 OMC Manifold

P/N 51430 Manifold assembly for port or starboard side models
OEM 3857723 $266.95

Manifold parts 5.7 liter 1990 and up

Manifold parts 5.7 liter 1990 and up

P/N 51430 stern drive model 5.0 to 5.7 liter manifold GM 305-350 CID V8
Years 1989 and after 3857723

Including:
P/N 51430 Riser exhaust assembly 3857723
P/N 31100 Gaskets 3852468
P/N 33810 Gasket for elbow 3850496
P/N 22487 Stud (2 units) 3852467
P/N 21248 Flange serrated nuts 3853404
P/N 13982 Straight fitting kit
P/N 13992 Drain plug kit
P/N 80140 304174 O Ring
P/N 13970 fitting 3852538

May be required but not included:

P/N 51330 assembly
P/N 22316 Screw 3852830
P/N 21493 Lock-washer 3852002
P/N 21675 Washer (5 units) 3852058
P/N 89224 Hose 3852696
P/N 89222 Hose 3852741
P/N 01068 Clamp 3853860
P/N 01090 hose clamp 3852604
P/N 22379 Plug
P/N 21896 Plug 315713

OMC V6 1986 to 1990
OMC V6 1986 to 1990
P/N 51470 / 51472 4.3 and 4.3 H.O. series GM 262 C.I.D. V6 800 series for years OEM 984221 port side and 984222 starboard side 1986 to 1990.

Included in exploded view drawing:
P/N 51472 Starboard side V6 1986 -1990 assembly with cap and elbow fitting
P/N 51470 port side V6 1986 -1990 assembly with cap and elbow fitting
P/N 32170 gasket 3853412
P/N 13980 Water drain
P/N 13992 Drain plug kit
P/N 80140 o rings 304174
P/N 22485 stud 909222
P/N 21248 nut 908700
P/N 21493 Lock-washers 3852002
P/N 13970 fitting 3852538
P/N 89228 hose 912328
P/N 89230 hose 3852742
P/N 01090 clamp 3852604
P/N 01200 clamp 984387
V6 1991 and up
V6 1991 and up
51500 OMC Manifold

51480 OMC V6 manifold

P/N 51480 V6 has both side the same. 4.3 liter exhaust assembly
Years 1991 and after GM 262 CID V6 3857656.

Included in kit:
P/N 51480 4.3 Liter V6 1991 and up GM 262 CID exhaust assembly.
P/N 32170 #3853412
P/N 33810 #3850496
P/N 22487 Stud (2 units) 3852467
P/N 21248 Nut 3853404
P/N 13982 Straight fitting kit
P/N 13992 Drain plug kit
P/N 80140 O Ring 304174
P/N 13970 fitting 3852538
Volvo Penta SX
Volvo Penta SX
Volvo Penta Cobra SX
P/N 51430 unit
3857944-7 and
P/N 51330 Elbow 3857723
both sides same 1994 and up V- 8 GM Small Block
51500

51500 OMC Manifold

P/N 51500 Unit for 7.4 liter 454 cubic inch. 8.2 liter 502 cubic inch. V8
Years 1991 and after.

Kit includes
P/N 51500 Manifold OEM 3861459
P/N 33810 and drain plug kit.
P/N 33760 Gasket OEM 3852472
P/N 33810 Gasket OEM 909786 $4.00 
P/N 13982 Straight fitting
P/N 13992 Drain plug kit 22-806608A02-4B
P/N 80140 o ring OEM 304174
P/N 13970 Elbow Fitting OEM 3852538 

33810 Gasket

33810 Gasket

39910 Engine gasket set

39910 Engine gasket set

39790 set

39790 set

39771 exhaust set

39771 exhaust set

39790 OMC gasket set

39790

P/N 39910
Years 1975 to 1998 and Volvo 1994 and never. Chevy V8 for 5.0 liter 305 cubic inch, 350 CID 5.7 liter V8 small blocks

P/N 39920
Ford V8, 5 liter 302 cubic inch and 5,8 liter, 351 cubic inch small blocks. Years 1977 to 1996 and Volvo years 1994 to 1996.

P/N 39770
Chevy large port  4 cylinder 2.5 liter 153 cubic inch, 120 hp. 3.0 liter 181 cubic inch and 140 hp. years 1985 to 1990

P/N 39780
4 cylinder 2.5 liter 153 cubic inch 100 hp. and 120 hp. engine years 1965 to 1985

P/N 39790
Chevy 4 cylinder 140 hp. 3 liter 181 cubic inch and 140 hp. engines years 1973 to 1984

P/N 39800
Ford V8 large block 460 cubic inch 7.5 liter years 1987 to 1990

P/N 39771
GLM marine aftermarket Chevy 4 cylinder, 3.0 liter 181 cubic inch engine 1985 to 1988. Volvo 3.0 liter 1993 and newer

P/N 39773
Riser kit for Chevy V6 4.3 liter 262 cubic inch years 1991 to 1998 Volvo years 1992 and newer.

P/N 39940
Chevy V8 large block 7.4 liter 454 cubic inch and 8.2 liter 502 cubic inch engines

P/N 39776
Ford 4 cylinder 2.3 liter engine years 1987 to 1990

P/N 39774
Chevy V6 4.3 liter 262 cubic inch Volvo engine year 1991 and older

P/N 39775
Chevy V8 5.0 liter 305 cubic inch, 5.7 liter 350 cubic inch Volvo engine 1993 and older.

39690 GM Engine rebuild kit

39690 GM Engine rebuild kit