CAT Block Heaters: C15, C13, C7, 3406 & 3306
Nearly every on-highway CAT — C10 through C16, 3176 through 3406E — takes its coolant heater in the oil cooler, replacing a threaded plug in the cooler bonnet. That makes CAT one of the easiest heavy-duty installs: no freeze plugs to punch out, just a pipe plug to swap for an element. The catch is that the port size changed across generations (1" NPT, then 1-5/16", then 1-3/16"), so the year and ACERT designation matter.
The mid-range engines are the exception: the C7 and its 3126/3116 ancestors use a 44 mm freeze-plug heater in the block, and the old 3208 offers both styles. All part numbers below are Zerostart / Phillips & Temro, with Kat's equivalents where the catalogs agree.
Heater part numbers by application
Part numbers from the Zerostart / Phillips & Temro heavy-duty application guide, with Kat's equivalents where both catalogs list the engine. Numbers are occasionally superseded — confirm against a current catalog or dealer before ordering.
C13 ACERT & C15 ACERT (2007 and newer)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500111 | 1,500 W | 120 V | 1-3/16" STOR | Immersion | 3600008 |
Replaces the 1-3/16" plug in the rear of the oil cooler, right-hand side of the engine.
Kat's equivalent: 30216 (1,500 W / 120 V).
C9, C15, C16 ACERT (2004–2006)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500077 | 1,500 W | 120 V | 1-3/16" thd | Immersion | 3600008 |
| 3500076 | 1,500 W | 240 V | 1-3/16" thd | Immersion | 8608377 |
Replaces the 1-3/16" threaded plug in the rear of the oil cooler bonnet.
Kat's equivalent: 30213 (1,500 W / 120 V).
C11 & C13 ACERT (2004–2006)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500075 | 1,500 W | 120 V | 1-5/16" STOR | Immersion | 3600008 |
| 3500074 | 1,500 W | 240 V | 1-5/16" STOR | Immersion | 8608377 |
Replaces the 1-5/16" threaded plug in the rear of the oil cooler.
Kat's equivalents: 30212 (120 V) / 31212 (240 V).
C9, C15, C16 (pre-ACERT), 3408
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 8600090 | 1,000 W | 120 V | 1" NPT | Immersion | 3600008 |
| 8600120 | 1,000 W | 240 V | 1" NPT | Immersion | 8608377 |
| 8605556 | 1,500 W | 120 V | 1" NPT | Immersion | 3600008 |
| 8600260 | 1,500 W | 240 V | 1" NPT | Immersion | 8608377 |
Installs in the oil cooler rear bonnet.
Kat's equivalents: 30313/31313 (1,000 W) and 30303/31303 (1,500 W).
C10, C12, 3196; 3406 with BrakeSaver (1994+)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500013 | 1,500 W | 120 V | 1" NPT | Immersion | 3600008 |
| 3500031 | 1,500 W | 240 V | 1" NPT | Immersion | 8608377 |
Replaces the 1" NPT plug in the oil cooler (rear on C10/C12/3196; front bonnet on BrakeSaver 3406s).
Kat's equivalents: 30207 (120 V) / 31207 (240 V).
3406 & 3406E (except 1998 models)
Not for the 1998 3406E or 15.8L 600 hp engine — see next table.
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 8600090 | 1,000 W | 120 V | 1" NPT | Immersion | 3600008 |
| 8600120 | 1,000 W | 240 V | 1" NPT | Immersion | 8608377 |
| 8605556 | 1,500 W | 120 V | 1" NPT | Immersion | 3600008 |
| 8600260 | 1,500 W | 240 V | 1" NPT | Immersion | 8608377 |
Without BrakeSaver: replaces the 1" pipe plug in the oil cooler rear bonnet. With BrakeSaver (through 1993): install in the front bonnet.
3406E, 3456, 15.8L 600 hp (1998 models only)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500033 | 1,500 W | 120 V | 1" NPT | Immersion | — |
Installs in the oil cooler rear bonnet. The unique 1998 design is NOT interchangeable with 8605556.
C7 ACERT (2004–2007), 3126/3126B, 3116, 3114, pre-2004 C7
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500015 | 1,000 W | 120 V | 44 mm | Freeze plug | 3600048 |
| 3500016 | 1,000 W | 240 V | 44 mm | Freeze plug | — |
| 3500081 | 1,500 W | 120 V | 44 mm | Freeze plug | 3600048 |
Replaces the core plug at the centre of the right side of the block. Kit includes a high-temperature cordset.
3306, 3304 (with oil cooler)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 3500043 | 1,000 W | 120 V | 3/4" NPT | Immersion | 3600008 |
| 8600988 | 1,000 W | 240 V | 3/4" NPT | Immersion | 8608377 |
| 8601011 | 1,500 W | 120 V | 3/4" NPT | Immersion | 3600008 |
| 8601054 | 1,500 W | 240 V | 3/4" NPT | Immersion | 8608377 |
Replaces the 3/4" pipe plug at the rear of the oil cooler on the left side of the engine.
3208 (636 CID)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 8602549 | 1,000 W | 120 V | 3/4" NPT | Immersion | 3600008 |
| 8602514 | 1,000 W | 240 V | 3/4" NPT | Immersion | 8608377 |
| 8602611 | 1,500 W | 120 V | 3/4" NPT | Immersion | 3600008 |
| 8602573 | 1,500 W | 240 V | 3/4" NPT | Immersion | 8608377 |
Swivel-style heater replacing the 3/4" pipe plug on the front of the engine. Freeze-plug alternative: 8602816 (600 W, 44 mm, requires two heaters on the 3208).
3176 (10.2L)
| Part no. | Watts | Volts | Size | Type | Repl. cord |
|---|---|---|---|---|---|
| 8601267 | 1,500 W | 120 V | 3/4" NPT | Immersion | 3600008 |
Replaces the 3/4" pipe plug on the right rear side of the engine. High-temperature cordset included.
Which port does your CAT use?
The fastest way to identify your heater is the oil cooler plug: on the right side of the engine, at the rear of the cooler, there's a large hex-head pipe plug. 1" NPT means the classic 8600090/8605556 family fits. The ACERT generations moved to O-ring straight-thread ports — 1-5/16" on C11/C13 (2004–06) and 1-3/16" on C9/C15/C16 (2004–06) and everything 2007+. If you're not sure, pull the plug and measure; the thread families are not interchangeable and forcing the wrong one strips the cooler bonnet.
Installation on any of the oil-cooler heaters is the same routine: drain coolant below the port, swap the plug for the element, refill, burp, and only then plug in. The 44 mm freeze-plug heater on C7/3126 engines is the harder job — the core plug has to come out of the block — and many owners have a shop do that one while paying for the part themselves.
FAQ
Where does the block heater go on a CAT C15?
In the oil cooler, right-hand side of the engine. 2007+ C15 ACERT: Zerostart 3500111 (1,500 W) in the 1-3/16" rear port. 2004–2006 ACERT: 3500077. Pre-ACERT C15/C16: the 1" NPT heaters 8600090 (1,000 W) or 8605556 (1,500 W) in the rear bonnet.
What block heater fits a CAT C7 or 3126?
A 44 mm freeze-plug heater in the centre of the right side of the block: Zerostart 3500015 (1,000 W/120 V) or 3500081 (1,500 W/120 V). The kit ships with a high-temperature cordset. The same heater covers the 3126, 3126B, 3116 and 3114.
Are CAT block heaters hard to install?
The highway engines (C10–C16, 3406) are among the easiest heavy-duty installs there are: the heater replaces a threaded plug in the oil cooler, so it's drain-swap-refill with hand tools. The C7/3126 freeze-plug heater is more work because the core plug must be removed from the block.
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