Headgaskets


#1

I just replaced the headgaskets in my 97 subaru legacy and was told by a mechanic to be wary of the bearings and camshaft. He said that on a car with 120,000 miles, replacing the headgaskets restores the top half of the engine to original compresion and since the bottom half is well worn, it may start to fail. He said that if I got through the next 3,000 to 6,000 miles w/o a problem, I should be okay. Should I be concerned about this? I just spent $1,800.00 for the headgaskets and won’t put the additional money into the car.

Thanks, Dan


#2

If you have maintained the engine properly and have not abused the engine, there is no reason why the bearings and camshaft should fail at that mileage. On my old '97 Outback, the headgaskets were replaced at ~120k, and the current owner (my brother) reports that the engine is still fine at its current mileage of ~155k.


#3

I don’t think it has to do with restoring compression, but if antifreeze contaminated the oil this may have damaged the bearing. It will take a few thousand miles to find out.


#4

I don’t get it.

Provided you have kept up with oil / filter changes I see no reason why the engine bottom end should be ‘well worn’. I’d agree with the camshaft taking a little wear since it is a an offset bearing face but it’s hardened and again shouldn’t show significant wear if oil changes have been kept up to spec.

Though new valve springs will put additional load on a worn cam, the cam isn’t subjected to any additional load from the increased compression, which will be insignificant from a new head gasket.

BUT…

If that engine was overheated due to a bad head gasket, or coolant found its way into the oil the crank / main bearings and camshaft could be compromised.

Other than that, I wouldn’t worry about it.


#5

If you’ve been maintaining the car properly, you should have little to worry about. At 120K miles, your Subaru engine should not be “well worn,” it should be good to go for another 120K miles.


#6

It’s entirely possible that failed head gaskets can cause the bottom end of the engine to fail; even if the bottom was fine before the head gasket problem.

Much depends on where those head gaskets failed. If the head gaskets allowed engine coolant to dilute the engine oil then the oil will not lubricate the rest of the engine properly. This will “wash out” the crankshaft bearings as it’s called along with damaging the crankshaft, cam lobes, lifters, etc.

If the head gaskets were replaced simply because of an external leak then this would not affect the bottom end.


#7

Don’t worry about it. Lots of cars have good compression and the lower end doesn’t fall out. Overhauling everything only guarantees a bigger bill.


#8

Is that 3,000 - 6,000 mile range about right for knowing if the head gasket repair was done properly and no other engine damage has occurred?

I’m at about 6,000 kms (3750 miles) since the HGs were done on my 99 Cadillac Seville STS, 130k miles on the car, car has been running great the entire time I’ve had it, with tons of power and no issues so far…


#9

It’s not a matter of guaranteeing a larger repair bill. It’s a matter of doing what is prudent and best for the long haul.
Someone who spends 1800 bucks for head gaskets and shortly afterwards starts seeing a flashing oil light or bearing rap will no doubt be very irritated with the mechanic when said mechanic tells them they need a new engine and the 1800 dollar HG job is all for nothing.

There’s no set time frame. It all depends on the exact circumstances behind the HG failure. Normally if there is a problem it will surface pretty quickly.


#10

I’m not sure for certain, that figure is what was told to me by a mechanic who didn’t repair the headgaskets.


#11

thanks for the input