Hours vary Novato (415) 898-4842
Hamiltons automotive INC
Engine Repair and Oil Leak Diagnosis

Family-owned · Novato, CA

Engine Repair and Oil Leak Diagnosis

From minor seals to major engine work, we find the leak and fix what's actually causing it.

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Oil Leak Repair and Engine Diagnostics

An oil leak doesn't fix itself. Left alone, what starts as a weeping valve cover gasket turns into oil on the exhaust, low pressure warnings, and eventually a seized engine. At Hamiltons Automotive on First Street in Novato, we diagnose the source of the leak before recommending a single repair. Call 415-898-4842 and we'll tell you what we're actually looking at.

Engine oil leak repair ranges widely depending on where the leak originates and how long it's been running. A valve cover gasket is a straightforward job. A rear main seal or timing cover leak is a full disassembly. Oil pan gaskets, cam seals, oil cooler lines, and crankshaft seals each carry different labor requirements. What drives the cost up: mileage, engine design, whether other components need to come off to reach the seal, and whether the leak has caused secondary damage to belts, sensors, or mounts. Every job is different. Contact Hamiltons Automotive INC for an accurate estimate.

The Diagnosis

Finding Where the Oil Is Actually Coming From Actually

A leak at the bottom of the engine doesn't mean the bottom of the engine is where it started.

Oil travels. A drip on the oil pan floor might have originated two feet higher and run down the block before it found a place to collect. We don't guess at the source. We clean the area, run the engine, and trace the leak to its actual point of origin before quoting any work. That process takes more time than eyeballing it, but it's the only way to avoid fixing the wrong thing. If you're seeing oil spots in your driveway or smelling something burning off the exhaust, those are both signs worth chasing before the repair bill gets bigger. Pair this with a full diagnostic scan when the check engine light is on alongside the leak.
Classic car engine bay on the shop floor

Engine Leaks We Repair at Hamiltons

Most of these we see every week. None of them require sending you somewhere else.

  1. 01

    Valve Cover Gasket

    One of the most common leaks on high-mileage engines. Cork and rubber gaskets dry out and crack. We replace them and check the surrounding area for secondary damage before buttoning it back up.

  2. 02

    Rear Main Seal

    Labor-heavy but not unusual. The rear main seal sits between the engine and transmission, which means significant disassembly. We do this in-house. You won't get referred elsewhere.

  3. 03

    Oil Pan Gasket

    Low on the engine and easy to overlook until the leak is significant. Pan gasket failure often accelerates in stop-and-go driving. We drop the pan, clean the surfaces, and reseal properly.

  4. 04

    Head Gasket

    The leak you don't want to ignore. A blown head gasket can push oil into the coolant or let combustion gases into the oil. We diagnose it accurately before any teardown recommendation.

How We Work

What the Repair Process Looks Like

Three steps, no surprises.

  1. 01

    Clean, Run, Locate

    We degrease the engine bay, run the vehicle, and identify the exact origin point of the leak under controlled conditions. No assumptions.

  2. 02

    Quote the Real Fix

    We call you with what we found, what it takes to repair it, and what it costs. Work doesn't start until you've approved it. That's a hard rule here.

  3. 03

    Repair and Verify

    After the repair we run the engine again and check for seepage before the car leaves the shop. If it's still weeping, it doesn't leave.

Repair vs. Replacement: The Honest Answer

Most oil leaks are repairable. A seized engine, a spun bearing, or catastrophic oil starvation damage is a different conversation. If you're at that point, we'll tell you directly whether a rebuild or replacement makes more sense than pouring money into a repair that won't hold. We won't push a replacement to run up the ticket, and we won't oversell a repair on an engine that's cooked. Leo's been running this shop long enough to know the difference, and 4.7 stars across 111 Google reviews reflects customers who got straight answers, not upsells. If the engine is saveable, we'll save it. If it's not, we'll tell you before you spend money finding out the hard way. We also handle trucks and larger vehicles with the same approach.
Classic car engine bay on the shop floor

Symptoms That Mean Call Now, Not Next Week

01

Oil Pressure Warning Light

This one doesn't wait. A low oil pressure warning means the engine may not be getting adequate lubrication. Pull over. Don't drive it to the shop.

02

Burning Smell While Driving

Oil dripping onto the exhaust manifold burns off and smells like something's wrong. Because it is. That smell usually means the leak is active and close to a heat source.

03

Visible Puddle in the Driveway

Fresh oil is amber to brown. Dark black puddles mean it's been leaking for a while. If the spot is quarter-sized or bigger, the leak rate is worth taking seriously.

04

Engine Smoking at Idle

Blue or white smoke from under the hood at idle is often oil burning off a hot surface. It can also indicate a more serious internal leak. Either way, it needs a diagnosis.

05

Low Oil Level Between Changes

If you're topping off oil every few weeks but there's no puddle on the ground, the engine may be burning oil internally. That's a separate problem from an external seal leak and needs its own diagnosis.

06

ABS or Check Engine Light Alongside the Leak

Oil contamination can reach sensors and wiring. If you've got warning lights and a known leak, the two may be connected. We'll run a full scan through our diagnostic shop as part of the intake.

Marin County Drivers: What We See Most Often

  1. 01

    High-Mileage Seal Failure

    Gaskets and seals dry out past 80k-100k miles. Regular maintenance slows this. Deferred maintenance accelerates it. We see both.

  2. 02

    Import and Domestic Coverage

    Toyotas, Hondas, Fords, GMs, and everything between. We don't specialize in one make and refer out others. The lift doesn't care what badge is on the hood.

  3. 03

    No Referrals, No Subcontractors

    The work is done here, by the people here. When you drop the car off, it stays in the shop. We don't send it down the street.

Questions About Engine Repair

How much does engine oil leak repair cost?
It depends entirely on the source. A valve cover gasket is significantly less work than a rear main seal or head gasket. Labor time is the biggest variable because some seals require removing major components to access. We diagnose first, then quote. Every job is different. Contact Hamiltons Automotive INC at 415-898-4842 for an accurate estimate on your specific vehicle.
Is it cheaper to repair an engine oil leak or replace the engine?
For most leaks, repair is cheaper by a significant margin. External seal and gasket failures are repairable jobs. The math changes if the leak caused oil starvation damage, scored cylinder walls, or spun bearings. In those cases, we'll lay out the repair vs. replacement numbers honestly so you can decide. We don't have a financial incentive to steer you either direction.
Can a car with an oil leak be driven safely?
Short distances to a shop, maybe. Long distances or driving while ignoring the oil level, no. The risk is running the engine low on oil, which reduces lubrication to the bearings and can cause permanent engine damage within minutes. If the oil pressure warning light comes on, stop driving immediately. Topping off and watching it is acceptable for a day, not for a week.
What is the most common source of an engine oil leak?
Valve cover gaskets fail most frequently on higher-mileage engines, particularly four-cylinders. Oil pan gaskets are second. Rear main seals, timing cover seals, and cam seals are less common but more labor-intensive to address. The leak's location on the engine gives a strong initial indication, but we always verify the source before pricing any repair.
Will an oil leak trigger the check engine light?
Sometimes. Oil leaking onto an oxygen sensor, wiring harness, or other sensor can trigger fault codes. Oil consumption from an internal leak can also cause codes related to fuel mixture or catalytic converter efficiency. If your check engine light is on and there's a known leak, run the diagnostic scan first. The two issues may be directly connected.
How long does an engine oil leak repair take?
A valve cover gasket on a straightforward engine is typically a same-day job. A rear main seal or timing cover job usually requires the vehicle overnight or into the next day, depending on disassembly complexity. We'll tell you the expected turnaround when we quote the work. We don't commit to a timeline we can't keep.
Will an engine oil leak trigger the check engine light?
Sometimes. Oil leaking onto an oxygen sensor or wiring harness can trigger fault codes. Oil consumption from an internal leak can also cause codes related to fuel mixture or catalytic converter efficiency. If your check engine light is on alongside a known leak, the two may be directly connected. We run a full diagnostic scan as part of intake.
How long does an engine oil leak repair take at Hamiltons Automotive?
A valve cover gasket on a straightforward engine is typically a same-day job. A rear main seal or timing cover job usually requires overnight or into the next day, depending on disassembly complexity. We tell you the expected turnaround when we quote the work. We don't commit to a timeline we can't keep.

Bring It In. We'll Tell You Exactly What It Needs.

4.7 stars across 111 Google reviews. Leo's shop at 1032 First Street, Novato. Call to get it looked at.

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