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CriticalCommonCooling

BMW 3 Series: M42/M44 timing-case profile gasket failure — coolant into the engine oil (318i/318is/318ti)

M42/M44 timing-case profile gasket failure — coolant into the engine oil (318i/318is/318ti) is a common cooling fault on the BMW 3 Series on the 1990–1999 cars, and we rate it critical. Putting it right costs $2,200 to $3,800 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 88 documented faults on the BMW 3 Series.

Vehicle
BMW 3 Series
Engine
M42 / M44
Years
1990–1999
Fuel
petrol
System
Cooling

This page covers the BMW 3 Series as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All BMW 3 Series faults88 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Cylinder head or Timing chain yet. We would rather show none than show a picture of a different part.

What goes wrong

The four-cylinder M42 and its later M44 replacement seal the coolant passage between the cylinder head and the lower timing-chain case with a moulded rubber 'profile gasket'. When it hardens and splits, pressurised coolant is forced straight into the timing case and down into the sump, where it turns the oil into a grey emulsion and destroys the main and big-end bearings within a few hundred kilometres. Most surviving cars were repaired long ago with the revised gasket, but an unrepaired or badly repaired engine is a rebuild waiting to happen. The job needs the cylinder head off, so it is never a cheap fix. Six-cylinder E36s do not have this gasket.

What you would notice

  • Coolant level drops steadily with no puddle under the car
  • Creamy grey or mayonnaise-like film under the oil filler cap
  • Sweet coolant smell from the front of the engine when hot
  • Steam or white smoke from the front of the engine bay after a run
  • Oil level on the dipstick rising above the full mark

How to check it

Where to look. Front of the engine, in the joint between the underside of the cylinder head and the lower timing-chain case, hidden behind the plastic timing cover — four-cylinder M42/M44 engines only.

  1. Open the bonnet before the engine has been started and take the oil filler cap off — a creamy grey or mayonnaise-like film underneath means coolant is already in the oil, and that is a walk-away.

  2. Check the dipstick as well: the oil should be honey to black, never grey or milky, and never above full.

  3. Shine your phone torch down the front face of the engine where the black plastic timing cover meets the cylinder head and look for a crusty pink or white coolant trail.

  4. Note the coolant level in the expansion tank before the test drive and look again after it, and be suspicious of a tank that has obviously been topped up.

  5. Ask the seller for an invoice showing the profile gasket or head gasket work, who did it, and at what kilometres.

  6. If a workshop inspection is possible: have a BMW specialist pressure-test the cooling system cold and check for combustion gases and for coolant sitting in the timing case.

Parts involved: Cylinder head, Timing chain.

What it costs to put right

$2,200 to $3,800 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the timing-case profile gasket ever been replaced, and do you have the invoice?”
  • “Has this engine ever overheated or been run low on coolant?”
  • “Does the coolant need topping up between services?”

Now check the BMW 3 Series you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

  • Bavarian Autosport Blog — 'BMW M42 M44 Coolant Leak – 318i, 318is, 318ic, 318ti, Z3'
  • Tim Thurber technical write-up — 'BMW M42 318i: Timing Case Profile Gasket'
  • BimmerFest thread — 'M42 Timing Cover Gasket'
  • 318ti.org forum thread — 'Mysterious M44 Coolant Leak'

BMW 3 Series buyer questions

Is m42/m44 timing-case profile gasket failure — coolant into the engine oil (318i/318is/318ti) serious on a BMW 3 Series?

We rate it critical and common on the BMW 3 Series. The four-cylinder M42 and its later M44 replacement seal the coolant passage between the cylinder head and the lower timing-chain case with a moulded rubber 'profile gasket'. When it hardens and splits, pressurised coolant is forced straight into the timing case and down into the sump, where it turns the oil into a grey emulsion and destroys the main and big-end bearings within a few hundred kilometres. Most surviving cars were repaired long ago with the revised gasket, but an unrepaired or badly repaired engine is a rebuild waiting to happen. The job needs the cylinder head off, so it is never a cheap fix. Six-cylinder E36s do not have this gasket.

How much does it cost to fix on a BMW 3 Series?

$2,200 to $3,800 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which BMW 3 Series years are affected?

Our research records this fault on the 1990–1999 BMW 3 Series. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Open the bonnet before the engine has been started and take the oil filler cap off — a creamy grey or mayonnaise-like film underneath means coolant is already in the oil, and that is a walk-away. Check the dipstick as well: the oil should be honey to black, never grey or milky, and never above full. Shine your phone torch down the front face of the engine where the black plastic timing cover meets the cylinder head and look for a crusty pink or white coolant trail. Note the coolant level in the expansion tank before the test drive and look again after it, and be suspicious of a tank that has obviously been topped up. Ask the seller for an invoice showing the profile gasket or head gasket work, who did it, and at what kilometres. If a workshop inspection is possible: have a BMW specialist pressure-test the cooling system cold and check for combustion gases and for coolant sitting in the timing case. Look here: Front of the engine, in the joint between the underside of the cylinder head and the lower timing-chain case, hidden behind the plastic timing cover — four-cylinder M42/M44 engines only.