Morning guys, looking for advice please. Just purchased a 2.5 WRX and 2 days after realised the HG was leaking. The garage I got the car from have fixed it up and I have it back now but they mentioned as it's just been machined and had the gasket replaced there is no need to run it in. Is this correct?

 

Correct, unless I'm missing something....


Your engine is already run in unless its a new build?


In the olden days when tollerances were not as fine as they are now, there was a bigger requirement to safely run an engine-in to ensure all the component bed properly. Todays tolerances would mean there is less of a need, so it would deepened on who built the engine and to what tolerances.


I've heard some builders run an engine for say 2000 miles with various oil changes, and other builders rag it as soon as its built!

 

whilst i would take it steady until you prove the fault has been sorted, there isn't really anything to "run in" when **** simply a head gasket issue............

different if its had bearings, pistons, etc. as these are interference components and need to 'bed' into each other..........

style of running in (for us) would depend on intended use - race / competition engines are lucky to get 50miles whereas road engines i would warrant a longer more structured approach

 

Two points here:

1. You say it's been "machined"? where? How much? And did they fit a thicker gasket to it in order to compensate for any thickness machined off? If not, the compression ratio may well be out

2. When head gaskets go, for some reason, (dilution of oil???), the bottom end tends to follow suit quite quickly after rebuilding.

Ask me how I know?

 

bearings can get pinched causing them to deform.

 

Not long had my hg replaced by slowboy racing. Neil’s advice was just to take it easy for the first 100 miles and keep an eye on the oil and fluids. More so because the engine had been out I think.

 

I've been running a donor shortblock which was kindly given to me by member johnlogie,it suffered hg failure and sat in his lockup for a few years,I slapped on my heads using the old head bolts and cosmetic head gaskets,I've been running for 18 months as a daily circa 11k miles now @1.65bar and 400ish bhp,car runs sweet
I did expect the bearings to give up after reading it was a must to replace them post hg failure but just maybe I've been lucky so far?
I did take it a bit easy for a few month and kept it at 1.4bar but doubt that would make any difference.