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Head Gasket Blown


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Hi Guys haven't been on in ages as been enjoying Scoobert, but it has happened as it does to many people head gasket has gone.  The issue is to rebuild & who to perform this (2.5 to 3.5k seems common) or buy a 2nd hand long block & from whom to get it off of (JDM Racing motors in Montreal appear to have a good selection, but nothing particular in the UK I have seen yet).  Any assistance would be greatly appreciated.

Thanks

Mark 

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1 hour ago, Mark McDowell said:

Hi Guys haven't been on in ages as been enjoying Scoobert, but it has happened as it does to many people head gasket has gone.  The issue is to rebuild & who to perform this (2.5 to 3.5k seems common) or buy a 2nd hand long block & from whom to get it off of (JDM Racing motors in Montreal appear to have a good selection, but nothing particular in the UK I have seen yet).  Any assistance would be greatly appreciated.

Thanks

Mark 

I payed 1.7k for my engine rebuild after one of my head gaskets failed, 20-22 hours labour + new seals and cometic headgaskets.

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First off is it a 2.5 or a 2.0? also what mileage is it at?

Full cost of rebuild wont be know till its stripped an assessed to see what damage has been done.

2.5 will be a full crank up rebuild when the headgasket goes and i would question the knowledge of anyone who says different. 2.0 will be very dependant on mileage and whats found, however given the 2.0 finished in 2005 engine will be at least 14 years old so i would expect a refresh of the crank bearings will be a good idea while it's apart.

Build spec depends on what your plans are and how far you want to go.

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@Tidgy

Why would it require a full rebuild if the coolant never got into the oil and ruin the bottom end? If only blowing into the coolant side then the bottom end should be fine no, if passes an inspection? If coolant got into the oil then yes i agree with you. I am no mechanic but i am curious as to why on a 2.5 this is the case regardless of age/mileage, and why is this different for a 2.0 (agreed now that it is that old/mileage i would do the bottom as well)? I own a low mileage 2007 Hawkeye WRX, and now need to save more in my oh **** funds.

 

@Mark good luck

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1 hour ago, Siluro said:

@Tidgy

Why would it require a full rebuild if the coolant never got into the oil and ruin the bottom end? If only blowing into the coolant side then the bottom end should be fine no, if passes an inspection? If coolant got into the oil then yes i agree with you. I am no mechanic but i am curious as to why on a 2.5 this is the case regardless of age/mileage, and why is this different for a 2.0 (agreed now that it is that old/mileage i would do the bottom as well)? I own a low mileage 2007 Hawkeye WRX, and now need to save more in my oh **** funds.

 

@Mark good luck

 

Short version is the crank bearings are often found to have been damaged. I know a few folks who have been told that is bad advice and not needed only to have had bottom end failures within 1000 miles of having just the headgasket done. One of which ended up becoming very nasty and going to court, which they won i should add, but the costs were pretty big for that

 

 

As far as 2.0, they seem to be less suseptable to crank bearing damage when headgasket fails, how ever given the milage most of them are at now its pretty much a no brainer to refresh the bottom end while the heads are off

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12 hours ago, Mark McDowell said:

Ah sorry omitted the details from the rebuild statement (big end bearings/clutch/cam belt/water and potentially oil pump) which I believe is classed as a refresh/rebuild.

 

has the engine been stripped and inspected or just diagnosed assemebled/running?

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18 hours ago, Tidgy said:

 

Short version is the crank bearings are often found to have been damaged. I know a few folks who have been told that is bad advice and not needed only to have had bottom end failures within 1000 miles of having just the headgasket done. One of which ended up becoming very nasty and going to court, which they won i should add, but the costs were pretty big for that

 

 

As far as 2.0, they seem to be less suseptable to crank bearing damage when headgasket fails, how ever given the milage most of them are at now its pretty much a no brainer to refresh the bottom end while the heads are off

That still does not answer the question. If coolant never got into the oil why is the bottom end trashed unless the engine was overheating, otherwise what destroys the bottom end? I agree is it is high mileage then it is a no brainer.

 

"Short version is the crank bearings are often found to have been damaged" by what?

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If it's been run for a long while with a leaking heagasket or has pushed all the coolant out and overheated . Then I think the bottom end tends to need to be refreshed . As combusting coolant in the bore could cause extra cylinder pressure or wear , leading to bottom end issues. 

Excessive heat also obviously causes wear throughout the whole engine too but if its caught early enough ,I can see why some would just do the headgaskets . Personally I'd refresh the bottom end on my own scoobs , as the majority of the labour is pulling the engine and getting the heads off but I do my own engine builds (so overall cost isn't much different) 

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7 hours ago, Siluro said:

That still does not answer the question. If coolant never got into the oil why is the bottom end trashed unless the engine was overheating, otherwise what destroys the bottom end? I agree is it is high mileage then it is a no brainer.

 

"Short version is the crank bearings are often found to have been damaged" by what?

As savage says, but what i can tell you is when the engines are stripped, experiance of dealing with dozens if not hundreds of 2.5 failures, finds the bearings are often found to be pinched and deformed, hence the rapid failure after.

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Thanks guys. Ok as I suspected then, if the motors overheated I can understand. If blowing for a long time that also makes sense. But not every bI will keep adding to my "oh sh*t fund". Good excuse to spend some money on new forged pistons etc.......

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My experience of doing not hundreds but well over a hundred 2.5s is most times bottom end within total spec when minimal HG leak and good state of tune.

The big killer is when left for months as having bad diagnosis as HG failure hard pick up in early stages then oil degradation and cylinder conditions can lead to bearing failure .

Hard driven impreza's always tend be worse for wear when stripped and you even see same crank and cam journal issues on ones with no HG leak as poor tuning or other running, service faults also related to journal wear, bad fuel and timing mapping being the most common followed by **** poor oil service .

I do 2.5 rebuilds on individual scenario/engine evaluation as no golden rule, done many gasket only on good example cars diagnosed early by myself and owners took advise do gasket immediately and no problems (and yes my work is guaranteed and I got no interest or benefit of come backs) 
The belief all bottom ends going be junked by slight coolant leak is not true, most junked by neglect of issue and poor tune state (would hardly ever see same issues bottom end on NA 2.5 block or lightly used turbo) other thing is some builders want best repair option for them not the owner .

As I say every time on this you got evaluate engines condition, usage and history and customer needs on individual case basis .
Example being a mum using a 80K XT untuned with impeccable service history and early detection of minimal head gasket leak most likely won't need a 3k plus rebuild and top end will be fine. Next one maybe 60K impreza weekend and track day, it mapped running more power guy been 3 shops over slight heating issue for almost year, service history and initial wide band checks, bore scope and sound probes give evidence it going be a full rebuild route only .

Biggest issue is owners always slow to deal with HG and why people don't do a HG upgrade as a precaution service point step is beyond me, it a well documented known issue on 2.5 NA and boosted . IF want more professional opinions on 2.5 look at US and Oz experience as they handle these in HUGE numbers .

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