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Fiat Tractor 55-60 60-90 79-90 80-90 90-90 100-90 tractor factory workshop manual download

Straightforward, practical how-to for replacing the heater core on Fiat Tractor models 55-60, 60-90, 79-90, 80-90, 90-90, 100-90. No fluff — theory, every component you’ll encounter, tools and parts, step‑by‑step procedure, bleeding and testing, and common failures with fixes. Assume a beginner-mechanic level; follow safety advice.

Summary (one line)
- The heater core is a small radiator inside the cab heater box. Replace it because it leaks, clogs, or corrodes — causing coolant loss, wet floor, smell, or no heat.

Theory — how the system works (analogy)
- Heater core = a tiny radiator. Hot engine coolant flows through it. A blower fan pushes air across the core and the warmed air goes into the cab. Think of it like a car’s radiator but inside the cab and used to heat people instead of cooling the engine.
- Coolant flow path: engine water jacket → hoses → heater core inlet → through core tubes/fins → outlet → return to engine/radiator (sometimes through heater control valve).
- Heater control: either a simple on/off valve or a lever/cable that routes coolant or isolates the core; blower speed and vent door direct airflow.
- Why problems matter: a leaking core dumps coolant into the cab and the cooling system which can overheat the engine. A clogged core restricts heat transfer and air feels cold even if the engine is hot.

Components (every component you’ll meet)
- Heater core (matrix): brass/steel/aluminum tube-and-fin radiator inside heater box.
- Heater box (heater housing/matrix housing): enclosure mounted in the cab/firewall holding the core, seals, ducts and flaps.
- Inlet and outlet heater pipes/pass-throughs (bulkhead fittings): metal pipes through the firewall connecting engine hoses to heater core.
- Heater hoses: rubber hoses from engine to heater inlet/outlet.
- Hose clamps: screw (worm-drive), pinch/ear, or spring clamps.
- Heater control valve (if present): mechanical/vacuum/lever valve in one hose or near firewall controlling coolant flow to heater core.
- Blower motor (fan) and resistor: forces air through core; may be mounted on heater box.
- Air ducts, flaps, seals, vents: direct warm air into cab; foam seals prevent bypass.
- Fasteners: screws, bolts, clips holding heater box and dash panels.
- Gaskets, O‑rings, rubber seals: at bulkhead fittings and between heater box and firewall/dash.
- Drain/fill/coolant system components: radiator cap, drain petcock, expansion tank.
- Tools you’ll use (see Tools section).

Symptoms that indicate heater core needs replacement
- Sweet smell in cab (antifreeze), visible coolant inside cab or on cab floor.
- Wet carpet or a damp mat under the cab floor.
- Engine overheats or coolant level drops with no external leak.
- No or weak cabin heat despite normal engine temperature.
- Discolored/foamy coolant or sludge in cooling system (indicates internal corrosion/clogging).
- Visible corrosion or damage when inspecting heater core/bulkhead.

Safety and prep (do these first)
- Work on a cool engine. Hot coolant can scald. Never open radiator cap hot.
- Wear gloves and eye protection. Antifreeze is toxic — keep pets and kids away.
- Have a drain pan and rags. Capture used coolant and dispose properly per local regs.
- Disconnect battery negative terminal if you’ll work on wiring or near the battery.
- Work in a ventilated area; keep fire extinguisher handy.
- Note: on tractors you may need to remove side panels, steps or cab flooring to access heater box — protect painted surfaces.

Tools and consumables (typical list)
- Metric socket set (8–19 mm), ratchet, extensions
- Screwdrivers (flat and Phillips)
- Pliers: needle-nose, hose clamp pliers
- Utility knife or hose cutter (for old hoses)
- Drain pan and funnel
- Torque wrench (if you have specified bolts; otherwise snug)
- Flashlight or work lamp
- Replacement heater core (correct model)
- New heater hoses if old hoses are brittle (recommended)
- New clamps (worm-drive or replacement type)
- New O‑rings/gaskets for bulkhead fittings (if applicable)
- Coolant (correct type and ratio for Fiat tractor)
- Gasket sealant (only if required by new gasket instructions)
- Shop towels, gloves, disposable container for used coolant
- Optional: radiator pressure tester, vacuum pump for bleeding, multimeter for blower testing

Preparation steps (before disassembly)
1. Read the parts manual or confirm which heater core fits your model (core orientation, inlet/outlet locations).
2. Park on level ground and secure tractor (park brake).
3. Cool engine completely.
4. Drain coolant: place drain pan under radiator or use lower radiator hose/petcock to drain coolant until level is below heater hoses. You want minimal coolant in heater hoses and core before disconnecting — drain enough.
- If tractor has a drain petcock on block or radiator, open it. Save coolant if relatively clean, or dispose and refill fresh.
5. Remove battery negative (if working near battery/wiring).

Access — remove panels and controls
- On these Fiat tractors the heater box is inside the cab/floor area and fastened to the firewall. Typical access steps:
1. Remove seats if necessary to reach floor panels.
2. Remove rubber mat and any floor coverings.
3. Remove lower dash or access panels. There are screws/bolts that retain the heater box cover or the box itself.
4. Remove side engine panels if they block access to hoses and bulkhead fittings.
5. Label or photograph controls, cables and vacuum lines before disconnecting to ensure correct reassembly.

Disconnection of hoses and controls
1. Identify and mark inlet (hot) and outlet lines. Mark which hose goes to which pipe (paint or tape). Orientation matters for fit.
2. Loosen hose clamps on heater hoses at the engine side and at the bulkhead. If hose is stubborn, cut it off near fitting with a knife—be ready to catch coolant.
3. Disconnect heater control cable/valve linkage from the valve or flap (if present). Remove electrical connectors from blower if you need to remove box.
4. If you have a heater control valve in the hose, remove it intact if reusing or remove and replace.

Removing heater box / extracting heater core
- Steps vary by tractor layout; general approach:
1. Remove screws/bolts holding heater box cover or box to firewall. Keep fasteners organized.
2. Remove blower motor housing or disconnect blower if it prevents box removal (careful with wiring).
3. Once cover is off, you will see the heater core seated in the heater box. It may be held by clips or bolts and sealed with foam gaskets.
4. Carefully unclip or unbolt the heater core. Note orientation of inlet/outlet tubes and how seals contact the bulkhead.
5. Withdraw core straight out of the box. Some coolant may spill — have rags and pans ready.

Inspection and what to look for
- Inspect heater core: look for corrosion, pinhole leaks, clogged fins, crushed tubes.
- Inspect hoses: soft, cracks, blisters, or collapse warrant replacement.
- Inspect bulkhead seals/O‑rings: replace if flattened or cracked.
- Inspect heater box: rust, broken mounting tabs, or foam seals that need replacement.
- Inspect blower and flaps: check for broken actuators or seized blower.

Installing the new heater core (detailed)
1. Compare new core to old: confirm inlet/outlet orientation and tube locations match.
2. Replace any bulkhead O‑rings/gaskets with new ones. Lightly lubricate O‑rings with coolant for easier installation.
3. Insert new core into heater box, aligning inlet/outlet tubes with firewall bulkhead holes. Ensure foam seals/gaskets seat fully; use new foam if provided.
4. Secure core with clips/bolts. Don’t over-tighten; bolts just secure core and gasket. If manufacturer torque exists use it; otherwise tighten snugly so gaskets compress uniformly.
5. Reinstall heater box cover, blower motor, and any ducts, ensuring vent flaps and seals are in correct positions.
6. Reattach heater control linkage and electrical connectors.

Reconnect hoses and clamps
1. Slide new or cleaned hoses onto fittings. Install hose clamps so they compress the hose over the ferrule/bulge — ensure clamp is positioned behind raised bead on fitting if present.
2. For worm-drive clamps, tighten until the hose compresses but don’t cut into hose. For ear clamps, crimp properly.
3. If a heater control valve was removed, re-fit or replace and secure its mounting and linkage.

Refill and bleed the cooling system (critical)
- Air trapped in the cooling system causes overheating and no heat in cab. Bleed carefully.
1. Refill radiator/expansion tank with recommended coolant mix. Leave cap off for bleeding.
2. If tractor has a bleed screw near thermostat housing or heater hose high point, open it.
3. Start engine and run at idle with heater on maximum heat and blower on high. This forces coolant through the heater core and helps expel air.
4. Watch coolant level and top up as air bleeds out. When bubbling stops and temperature stabilizes at normal operating temperature, top and close bleed screw(s) and radiator cap.
5. Cycle heater control between hot/cold and different blower settings while topping up to release trapped pockets.
6. Run to operating temp and recheck for leaks around hoses, bulkhead, and heater box.
7. After cool down, recheck coolant level and top if necessary.

Leak check, function check, and reassembly
- Check for coolant leaks: inspect under dash and around heater hoses after running engine to temp.
- Ensure blower works and vent flaps move. Test for hot air at vents (should heat as engine warms).
- Replace panels, mat, seat, battery connection. Dispose of used coolant.

Common things that go wrong and how to avoid/fix them
- Air trapped after reassembly: result = overheating or no heat. Fix by using bleed screw(s), heater-on-high, and repeat bleeding steps until no air.
- Hose clamp leak: hoses can leak if clamp placed wrongly or over-tightened (cuts hose). Use correct clamp type and position. Replace clamps if corroded.
- Wrong orientation of core: core tubes may not line up. Don’t force; confirm correct part before final closure.
- Blower motor wiring damaged: disconnect battery before working on blower; check connector pins before reconnection.
- Damaged firewall bulkhead fitting or rusted pipe ends: if corroded, replace bulkhead fittings or cut and fit repair pipes.
- Heater box gasket leaks: foam seals deteriorate — replace to prevent air bypass and interior leaks.
- Sludge/clog in new core quickly: caused by contaminated coolant left in engine. Flush cooling system thoroughly before installing new core. Consider professional flush if heavy sludge.
- Electrolysis/corrosion causing repeated failures: poor ground or electrical issues can cause rapid corrosion. Check engine/chassis ground straps and alternator earths.
- Leaking core after install: often due to improper seating of seals or over-tightened bolts. Remove and re-seat with new gasket.

Tips and best practices
- Replace hoses and clamps at same time as core if hoses are old — cheap insurance.
- Flush the cooling system if coolant is discolored or has sludge. New core will clog fast if system is dirty.
- Use OEM or high-quality aftermarket parts; cheaper cores can fail early.
- Keep a camera/phone to take photos during disassembly so reassembly is straightforward.
- Label hoses and wires with tape/pens to avoid mistakes.
- If you don’t have patience to bleed air thoroughly, rent a vacuum fill or pressure-fill tool — it makes bleeding easier.
- If the cab floor is soaked and moldy, dry and disinfect before reinstalling carpet/mats.

Estimated time and difficulty
- Difficulty: moderate. Access can be tight; requires basic hand tools and patience. If heater box removal is extensive, allow more time.
- Time: 3–8 hours depending on access and your experience. If you must remove cab components or floors, plan for longer.

Final checklist before calling it done
- No coolant leaks at hose connections or bulkhead.
- Heater delivers hot air after warm-up.
- Coolant level stable after first run and rechecked when cold.
- All electrical connectors reattached; blower speeds work.
- Panels and fasteners reinstalled; no loose parts left under dash.

If it still won’t heat after a correct install and bleed:
- Check heater control valve operation (stuck closed).
- Verify coolant flow through hoses when engine warm (feel the inlet and outlet hoses — both should be hot; if inlet hot but outlet cool, restricted core).
- Check thermostat operation — a stuck open thermostat reduces cabin heat.
- Check for air still trapped — repeat bleeding.

No Yapping. Follow the steps, take photographs as you go, and replace hoses/gaskets and flush system if needed. Good luck; work safely.
rteeqp73

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