Mercruiser Thermostat Kits

Refine Parts List
Engine / Model :

Engine / Model

Beginning S/N

Ending S/N

Sierra Thermostat Kit

120/2.5L (2)2324347 UP 18-3650
140 (4 CYL)/3.0L 2508261 UP 18-3650 (8)
3.0L/3.0LX C856559 UP 18-3650
165 2770032 5813433 18-3650
165/3.7L (4 CYL) 6916779 UP 18-3667
170 (4 CYL) 6916779 UP 18-3667
175/4.3L, 4.3LX (262 CID) (3)B527955 UP 18-3668
175/4.3L, 4.3 LX (262 CID) (4)B527955 UP 18-3668
175/4.3L, 4.3 LX (262 CID) (4)F001220 UP 18-3648
180/3.7L-LX (4 CYL) 6916779 UP 18-3667
185 (229 CID) 6330183 6919655 18-3668
185 (262 CID) A331455 B527954 18-3668
190 (4 CYL) 6916779 UP 18-3667
200 GM 6218462 B525981 18-3668
200/5.0L 0B525982 0F600999 18-3647
200/5.0L GM (3)B525982 UP 18-3668
200/5.0L GM (4)B525982 UP 18-3648
205 (262 CID) A331455 B527954 18-3668
205/4.3L, 4.3LX (262 CID) (3)B527955 D714369 18-3668
205/4.3L, 4.3 LX (262 CID) (4)B527955 D714369 18-3668
205/4.3L, 4.3 LX (262 CID) (4)F001220 UP 18-3648
215 FORD 3040411 UP 18-3651
215 FORD MCM/MIE 3040411 3385720 18-3646
225 FORD MCM/MIE 3385721 4176999 18-3646
225 GM 2278647 2399197 18-3668
225 GM 2399198 2694014 18-3651
225/225S FORD 3385721 UP 18-3651
228 GM MCM/MIE 4765100 6218461 18-3646
228 GM 4765100 6218461 18-3651
228 GM 6218462 B525981 18-3668
230 GM 6218462 B525981 18-3668
230 MIE 5907058 0B5225505 18-3646
230 GM IB (5)5907058 B522505 18-3668
230 GM IB (6)5907058 B522505 18-3651
230/5.0L GM IB (5)B522506 B525981 18-3668
230/5.0L GM IB (5)B522506 B525981 18-3648
230/5.0L GM IB (6)B522506 B525981 18-3651
230/5.0L-LX GM (3)B525982 F600999 18-3668
230/5.0L-LX GM (4)B525982 UP 18-3668
230/5.0L GM IB (4)B522506 B525981 18-3648
230/5.0L-LX GM B525982 F600999 18-3648
230/5.0L MIE 0B522506 0B788151 18-3646
230/5.0LX GM 0B525982 0F600999 18-3647
233 FORD 4173000 UP 18-3651
233 FORD MIE 4173000 4902304 18-3646
250 GM 2314301 2639854 18-3651
250 GM 4768000 4908849 18-3651
250 GM 4768000 4908849 18-3646
250 GM MCM/MIE 2314301 2639854 18-3646
250 GM MCM/MIE 4175500 5907057 18-3646
255 FORD 3258728 UP 18-3651
255 FORD MCM/MIE 3258728 4178299 18-3646
255 GM 4175500 4767999 18-3651
260 GM 4908850 6218461 18-3651
260 GM 6218462 B525981 18-3668
260 GM 4908850 6218461 18-3646
260 GM IB (5)5907058 B522505 18-3668
260 GM IB (6)5907058 B522505 18-3651
260 MIE 5907058 0B522505 18-3646
260/5.7L GM IB (5)B522506 B525981 18-3668
260/5.7L GM IB (5)B522506 B525981 18-3668
260/5.7L GM IB (5)B522506 B525981 18-3648
260/5.7L GM IB (6)B522506 B525981 18-3651
260/5.7L GM (3)B525982 F600999 18-3668
260/5.7L GM (4)B525982 F600999 18-3668
260/5.7L GM (4)B525982 F600999 18-3648
260/5.7L GM 0B525982 0F600999 18-3647
260/5.7L MIE 0B522506 0F024999 18-3646
262 MAG ALPHA 0F803800 0K999999 18-3647
262 MAG BRAVO 0F803800 0K999999 18-3647
350 Mag B525982 F600999 18-3668
4.3L/LX GM 0F000878 0F601126 18-3647
4.3L/LX/LXH ALPHA 0F601127 0K999999 18-3647
4.3L/LX/LXH BRAVO 0F601127 0K999999 18-3647
4.3L/LH/EFI ALPHA 0L010044 UP 18-3647
4.3L/LH/EFI 0L010044 UP 18-3647
5.0L/EFI ALPHA 0L012052 UP 18-3647
5.0L/EFI BRAVO 0L012052 UP 18-3647
5.7 GM ALPHA 0F225560 0K999999 18-3647
5.7 GM BRAVO 0F225560 0K999999 18-3647
5.7L/EFI GM ALPHA 0L010037 UP 18-3647
5.7L/EFI GM BRAVO 0L010037 UP 18-3647
5.7 GM (SKI) A338553 B514626 18-3668
5.7L SKI 0B514627 UP 18-3647
5.7 GM SKI/BRAVO (3)B514627 UP 18-3668
5.7 GM SKI/BRAVO (4)B514627 UP 18-3668
5.7 GM SKI/BRAVO (4)B514627 UP 18-3648
5.7L MIE 0F025000 0F622099 18-3647
5.7L MIE 0F622100 0K999999 18-3647
5.7L MIE 0F622100 0K999999 18-3647
5.7L MIE 0L002003 UP 18-3647
270 GM 2851074 3077735 18-3651
270 GM MCM/MIE 2851074 3385720 18-3646
280 GM 4176250 4770199 18-3646
280 GM TRS 4176250 4770199 18-3651
300 MR/TRS GM 6668677 B430367 18-3668
320 GM EFI A543604 UP 18-3651
320 GM 0A543604 0C622418 18-3646
325 GM MCM/MIE 2278747 3780449 18-3646
325 GM 2278747 2313964 18-3668
325 GM 2313965 3042730 18-3651
325 GM 3042731 UP 18-3651
330 GM 4623115 UP 18-3651
330 GM MCM/MIE 4623115 0B816540 18-3646
330 GM W/BW (5)6083145 UP 18-3668
330 GM W/BW (6)6083145 UP 18-3651
340/7.4L GM IB (5)5889914 UP 18-3668
340/7.4L GM IB (5)5889914 UP 18-3668
340/7.4L GM IB (6)5889914 UP 18-3651
340/7.4L MIE 5889914 0D715493 18-3646
350 MAG 0B252882 0K999999 18-3647
350 MAG 0B252882 0K999999 18-3647
350 MAG SKI 0D505450 0K999999 18-3647
350 MAG EFI SKI 0F215561 0K999999 18-3647
350 MAG MPI/MIE 0L010019 UP 18-3647
350 MAG MPI SKI 0F350583 UP 18-3647
SCORPION SKI 0F800000 UP 18-3647
7.4 BRAVO GM (3)B771113 D603117 18-3668
7.4 BRAVO GM (4)B771113 UP 18-3668
7.4 BRAVO GM (4)D603118 UP 18-3648
7.4L W/HURTH IB (5)C391564 D715493 18-3668
7.4L W/HURTH IB (6)C391564 UP 18-3651
7.4L W/HURTH IB D715494 UP 18-3648
7.4L/LX GM 0F352000 0K999999 18-3647
7.4L MPI/TBI 0F563052 UP 18-3647
7.4L MIE 0C391564 0D715493 18-3646
7.4L MIE 0C391564 0F349999 18-3646
7.4L MIE 0D715494 0F820141 18-3646
7.4L MIE 0F820142 0K999999 18-3647
7.4L MIE 0F820142 0K999999 18-3647
350 GM 3780450 UP 18-3651
350 GM (MAGNUM) A635178 B525981 18-3668
350 GM (MAGNUM) (3)B525982 UP 18-3668
350 GM (MAGNUM) (4)B525982 UP 18-3668
350 GM (MAGNUM) (4)B525982 UP 18-3648
350 MIE 3780450 4623109 18-3646
370 GM 4179554 6721527 18-3646
370 TRS GM 4179554 6721527 18-3651
370 TRS GM 6721528 UP 18-3668
390 GM 2781129 2825059 18-3651
390 GM MCM/MIE 2781129 3042731 18-3646
400 GM 4179554 0B457644 18-3646
400 TRS GM 4179554 UP 18-3651
420 GM A398941 UP 18-3651
420 GM 0A398941 0B622418 18-3646
440 TRS GM 4179554 UP 18-3651
454 GM MAGNUM/ALPHA (3)A631894 B785148 18-3668
454 GM MAGNUM/BRAVO (4)A631894 UP 18-3668
454 GM MAGNUM/BRAVO (4)B721206 UP 18-3648
454 MAG MCM/SKI 0F305000 0K999999 18-3647
460 TRS GM 4179554 UP 18-3651
470 4208730 6218036 18-3652
470 6218037 UP 18-3667
485 5685394 UP 18-3652
488 6170297 UP 18-3667
500(Gen V) F213293 F615766 18-3651
502 EFI/MPI MCM 0F8026000 0K999999 18-3647
502 MAG MPI 0L017000 UP 18-3647
575 GM 0A677429 0D763716 18-3646
575 A677429 UP 18-3651
8.2L MIE 0D857200 0F350274 18-3647
8.2L MIE 0F350275 0F819619 18-3647
8.2L MIE 0D857200 0F819619 18-3647
8.2L MPI/MIE 0F819620 UP 18-3647
888 FORD 3108723 UP 18-3651
888 FORD MCM 3108723 4887829 18-3646
898/198 GM 4762210 6218461 18-3651
898/198 GM MCM/MIE 4762210 6218461 18-3646
898 GM 6218462 UP 18-3668

Engine / Model

Beginning S/N

Ending S/N

Sierra Thermostat Kit

Notes:
  • (2) : Cast Iron
  • (3) : Old Design
  • (4) : New Design
  • (5) : Std. Cooling
  • (6) : Closed Cooling
  • (8) : S/N 6229718 & up
Refine Parts List
Engine / Model :
Your Price: $15.98
Save: $5.59
(25% Off $21.57)
Part # 18-3568 ValueShip™ Eligible
Hurry! Only 1 left in stock
No Reviews  |  Write Review  |  Ask Question
Replaces OEM part #
  • MERCURY MARINE 99155T1
Fits:
  • Model 5.7MIE, Year 1998-2001, Serial# OL002003 & Up
  • Model MX6.2LMPI, Year 2000-2001, Serial# OL680003 & Up
  • Model 454 Horizon MIE, Year 1998-2001, Serial# OL002200 & Up
  • Model 502 Mag. MPI, Year 1998-2001, Serial# OL017000 & Up
Your Price: $16.73
Save: $9.03
(35% Off $25.76)
Part # 18-3644 ValueShip™ Eligible
Hurry! Only 1 left in stock
Contains:
  • (1) 18-3649 Thermostat 160 Degree - replaces O.E.# 807252T2
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2917 Thermostat Cover Gasket - replaces O.E.# 27-53045-1
Your Price: $16.22
Save: $5.77
(26% Off $21.99)
Part # 18-3646 ValueShip™ Eligible
Replaces OEM part #
  • MERCURY MARINE 807252Q3
Contains:
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
  • (1) 18-2917 Thermostat Housing Gasket - replaces O.E.# 27-53045-1, 27-33918
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2834 Thermostat Cover Gasket - replaces O.E.# 27-60208
Your Price: $22.49
Save: $12.32
(35% Off $34.81)
Part # 18-3647 ValueShip™ Eligible
Replaces OEM part #
  • MERCURY MARINE 807252Q5
Contains:
  • (1) 18-3649 Thermostat - replaces O.E.# 807252-2
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-2552 Thermostat Cover Gasket - replaces O.E.# 27-33179-2
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-7173 O-Ring - replaces O.E.# 25-30224
  • (1) 18-2917 Thermostat Housing Gasket - replaces O.E.# 27-53045-1, 27-33918
Your Price: $17.06
Save: $8.52
(33% Off $25.58)
Part # 18-3648 ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
160 Degree
Your Price: $15.37
Save: $6.32
(29% Off $21.69)
Part # 18-3650 ValueShip™ Eligible
Hurry! Only 1 left in stock
Contains:
  • (1) 18-2831 Gasket - replaces O.E.# 27-47590-1
  • (1) 18-3550 Thermostat - replaces O.E.# 59078
Your Price: $14.25
Save: $6.14
(30% Off $20.39)
Part # 18-3651 ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Contains:
  • (1) 18-2554 Thermostat Cover Gasket - replaces O.E.# 27-90556
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2834 Thermostat Cover Gasket - replaces O.E.# 27-60208
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
Your Price: $18.12
Save: $8.73
(32% Off $26.85)
Part # 18-3652 ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Contains:
  • (1) 18-2555 Thermostat Cover Gasket - replaces O.E.# 27-89656-1
  • (1) 18-2843 Thermostat Cover Gasket - replaces O.E.# 27-74830
  • (1) 18-3552 Thermostat - replaces O.E.# 76270
Your Price: $15.32
Save: $7.90
(34% Off $23.22)
Part # 18-3667 ValueShip™ Eligible
Hurry! Only 1 left in stock
Contains
  • (1) 18-2555 Thermostat Cover Gasket - replaces O.E.# 27-89656-1
  • (1) 18-3555 Thermostat - replaces O.E.# 99155A1
Your Price: $14.52
Save: $5.55
(27% Off $20.07)
Part # 18-3668 ValueShip™ Eligible
Contains:
  • (1) 18-2552 Thermostat Cover Gasket - replaces O.E.# 27-33179-2
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2554 Thermostat Cover Gasket - replaces O.E.# 27-41812
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
  • (1) 18-7173 O-Ring - replaces O.E.# 25-30224
Your Price: $16.58
Save: $5.73
(25% Off $22.31)
Part # 18-3668D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Contains:
  • (1) 18-2552 Thermostat Cover Gasket - replaces O.E.# 27-33179-2
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2554 Thermostat Cover Gasket - replaces O.E.# 27-41812
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
  • (1) 18-7173 O-Ring - replaces O.E.# 25-30224
Your Price: $18.14 (Out of stock)
Save: $6.81
(27% Off $24.95)
Part # 18-3646D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Replaces OEM part #
  • MERCURY MARINE 807252Q3
Contains:
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
  • (1) 18-2917 Thermostat Housing Gasket - replaces O.E.# 27-53045-1, 27-33918
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2834 Thermostat Cover Gasket - replaces O.E.# 27-60208
(Out Of Stock)
Low Price Guarantee
Your Price: $29.02
Save: $9.66
(24% Off $38.68)
Part # 18-3647D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Replaces OEM part #
  • MERCURY MARINE 807252Q5
Contains:
  • (1) 18-3649 Thermostat - replaces O.E.# 807252-2
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-2552 Thermostat Cover Gasket - replaces O.E.# 27-33179-2
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-7173 O-Ring - replaces O.E.# 25-30224
  • (1) 18-2917 Thermostat Housing Gasket - replaces O.E.# 27-53045-1, 27-33918
Your Price: $20.64 (Out of stock)
Save: $7.79
(27% Off $28.43)
Part # 18-3648D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
160 Degree
(Out Of Stock)
Low Price Guarantee
Your Price: $18.39
Save: $5.73
(23% Off $24.12)
Part # 18-3650D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Contains:
  • (1) 18-2831 Gasket - replaces O.E.# 27-47590-1
  • (1) 18-3550 Thermostat - replaces O.E.# 59078
Your Price: $17.37
Save: $5.30
(23% Off $22.67)
Part # 18-3651D ValueShip™ Eligible
No Reviews  |  Write Review  |  Ask Question
Contains:
  • (1) 18-2554 Thermostat Cover Gasket - replaces O.E.# 27-90556
  • (1) 18-2553 Thermostat Cover Gasket - replaces O.E.# 27-47510
  • (1) 18-2834 Thermostat Cover Gasket - replaces O.E.# 27-60208
  • (1) 18-2844 Thermostat Cover Gasket - replaces O.E.# 27-48818-1
  • (1) 18-3551 Thermostat - replaces O.E.# 59137
Sierra
Average Customer Review for Thermostat Kit - 18-3644 - Sierra
Full StarFull StarFull StarFull StarFull Star Based On 2 Reviews | Write Review
Full StarFull StarFull StarFull StarFull Starkit
by Ronald from Mineola, New York on August 19, 2013
satisified
Was this review helpful?
Full StarFull StarFull StarFull StarFull StarLooks to be good quality
by Dwayne from Thunder Bay, Ontario on October 15, 2011
Installed this product and looks to be good quality.
Was this review helpful?
Average Customer Review for Thermostat Kit - 18-3646 - Sierra
Full StarFull StarFull StarFull StarEmpty Star Based On 2 Reviews | Write Review
Full StarFull StarFull StarFull StarFull StarHad what I needed in the kit
by Kerry from Midway, Kentucky on July 07, 2014
The right parts at a reasonable price, enough said.
Was this review helpful?
Full StarFull StarFull StarEmpty StarEmpty StarT-stat Review
by Robert from Louisville, Kentucky on August 15, 2011
Although this "kit" came with the gasket it didn't come with the retainer that's needed to hold it in place.
Was this review helpful?
Average Customer Review for Thermostat Kit - 18-3647 - Sierra
Full StarFull StarFull StarFull StarFull Star Based On 1 Review | Write Review
Full StarFull StarFull StarFull StarFull StarEverything needed if you're careful
by Joe from Cary, North Carolina on September 27, 2013
Everything you need to replace the thermostat. Decent quality parts. Do be aware that the sleeve surrounding the thermostat is not included and it is easy to damage it during removal. My advice - plan on being clumsy and go ahead and order a replacement sleeve, too.
(1 of 1 people found this review helpful)
Was this review helpful?
Average Customer Review for Thermostat Kit - 18-3650 - Sierra
Full StarFull StarFull StarFull StarFull Star Based On 5 Reviews | Write Review
Full StarFull StarFull StarFull StarFull Starthermostat
by John from Round Lake, Illinois on July 09, 2014
it works perfectly.
Was this review helpful?
Full StarFull StarFull StarFull StarFull StarWorks great!
by David from Jamesville, New York on August 15, 2013
Works great!
Was this review helpful?
Full StarFull StarFull StarFull StarFull Starthermostat kit
by William from Yucca Valley, California on August 14, 2013
perfect fit went on with no problems
Was this review helpful?
Full StarFull StarFull StarFull StarFull StarGreat item and price.
by Douglas from Derry, New Hampshire on September 08, 2012
I am pleased with the overall product quality, price, and speed of shipping.
Was this review helpful?
Full StarFull StarFull StarFull StarEmpty StarSofar, so good
by Ray from Fayetteville, North Carolina on February 05, 2012
Arrived in a timely manner however I don't plan on installing it for a few months. My boat is trailered and winterized right now and I will install the new thermostat in the spring.
Was this review helpful?
Average Customer Review for Thermostat Kit - 18-3667 - Sierra
Full StarFull StarFull StarFull StarFull Star Based On 1 Review | Write Review
Full StarFull StarFull StarFull StarFull StarSierra thermostat kit
by Rob from Grafton, North Dakota on August 16, 2011
iboats has a very competitve price and ordering was easy and efficient. They sent the correct product and it installed and worked flawlessly.
(1 of 1 people found this review helpful)
Was this review helpful?
Average Customer Review for Thermostat Kit - 18-3668 - Sierra
Full StarFull StarFull StarFull StarFull Star Based On 4 Reviews | Write Review
Full StarFull StarFull StarFull StarFull StarExcellent product
by Bruce from Lexington Park, Maryland on June 23, 2016
This kit cam complete with all gaskets needed to complete replacement of the thermostat. Well packaged and exactly as described.
Was this review helpful?
Full StarFull StarFull StarFull StarEmpty Starthermostat
by Robert from Bakersfield, California on March 10, 2016
Thanks,delivery was on time
Was this review helpful?
Full StarFull StarFull StarFull StarFull StarThermstat Kit 18-3668
by Gene from Kalamazoo, Michigan on October 16, 2015
Great product, easy install, working very well
Was this review helpful?
Full StarFull StarFull StarFull StarFull StarMercruiser stat kit
by William from Mahopac, New York on January 06, 2013
As described and price is good
(0 of 1 people found this review helpful)
Was this review helpful?
Q:
Will this kit work for a 1994 Mercruiser 5.7?
A:
We will need your engine serial number to confirm, let us know if you can provide that.
Q:
Serial number is F434126?
A:
You will need to provide the year, make and horse power of the engine.
Ask a question
Question & Answer Guidelines
This product ships in 1 business day.
Add to Cart and enter your Postal Code to determine the shipping charges and estimated delivery date.
Most products and orders leave our warehouse in 1 business day. However, select items may take more processing time. Alaska and Hawaii orders please add 1 additional warehouse processing day.
Standard Shipping Policies