What is the head warp spec for a Subaru?

Head Warp Specification for a Subaru
The head warp specification for a Subaru varies depending on the specific model and engine. However, Subaru is very specific about the allowable amount of cylinder head and engine casting warpage. According to Subaru, the warpage must be no greater than 0.035mm (0.0012 in), and the maximum grinding limit to correct a warped cylinder head is 0.1mm (0.004 in).
It is important to note that while Subaru heads are known for their compact size and design, which results in them rarely warping, it is still recommended to check the heads for warpage and correct them if necessary before installing new head gaskets. Many technicians resurface Subaru heads as a matter of course to remove any warpage and ensure proper surface finish for the gaskets.
If you suspect that the heads on your Subaru are warped, it is advisable to consult with a reputable machinist or mechanic who is familiar with Subaru engines and can provide expert advice on whether the heads need to be machined beyond Subaru’s specifications or if purchasing remanufactured heads is a better option.
Please note that the information provided is based on the available search results and may not cover all Subaru models and engines. It is always recommended to consult the specific service manual or seek professional advice for accurate and up-to-date information regarding your particular Subaru model and engine.

What is acceptable cylinder head warpage?

Always check with the automaker’s tolerance specifications, but a generally accepted maximum warp is about 0.003-inch on a V6 deck, 0.004-inch on a V8 deck and about 0.006-inch on a straight-six deck. The head deck is then checked in the opposite diagonal direction.

Will an engine run with a warped head?

You can, but if coolant gets into the oil it will wipe out the bearings. If you let it run out of coolant the heads will warp or crack. If enough water leaks into the cylinder the engine can hydrolock. Drive it no farther than the repair shop and park it to reduce the cost of the repair..

What are the symptoms of a warped head?

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• 1.1. White Smoke (Steam) From the Exhaust Pipe.
• 1.2. Low Coolant Level.
• 1.3. Engine Overheating.
• 1.4. Rough Running and Misfiring.
• 1.5. Combustion Gases In the Cooling System.
• 1.6. Illuminated Warning Lights.
• 1.7. Coolant-Oil Intermix.

How do you check for a warped head?

Set your feeler gauge at . 003 inch, and place the gauge between the straightedge and the cylinder head. If the feeler gauge fits in the gap, then your cylinder head is warped and must be machined flat. Set the straightedge at the other corners diagonally, and check the gap with the feeler gauge.

Why are Subaru head gaskets so bad?

The problem stems from the type of coating on the original gasket and the design. Almost all these engines leak here to some extent at some time in their lives. If you’ve had a diagnosis of a ‘blown gasket’ and are worried about the consequences of driving with this fault; please ask us to inspect your car.

How flat should a cylinder head be?

No matter what cylinder head gasket you’re using but especially on an mls to make sure there’s no out of flat. Conditions. That will affect the ceiling. Performance. Of the head.

Which Subaru models have head gasket problems?

A number of Subaru models are affected, however the most common failures include the 2.5 Liter SOHC engine used in the late 1999-2004, Forester, Impreza, Outback and Legacy.

At what mileage do Subaru head gaskets fail?

between 100,000 and 150,000 miles
The original head gaskets on a Subaru 2.5 engine tend to fail between 100,000 and 150,000 miles. Most replacement gaskets last just as long. Will the repair cause other problems for my Subaru? Head gasket replacement usually goes smoothly and doesn’t cause any other issues.

How much can a cylinder head be warped?

Most aluminum heads using a multi-layer steel (MLS) head gasket should have no more than 0.002-inch (0.05 mm) of total distortion (block plus head combined) in any direction.

What is the cylinder head is warped?

Warping of the cylinder head is caused by conditions similar to cracking, namely overheating. When a head is heated past normal operating temperatures, it expands past its limits. As it cools, the head often will not return to its original size or shape, instead settling into a more bent or distorted form.