Why Do Subaru Engines Knock??!
02 November 2016, 12:56 PM
#1
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Why Do Subaru Engines Knock??!
Hi All,
My family have owned many subaru's in the past and i currently own a classic in pristine condition sitting on Rota Formula Mesh.
All our Subaru's we have had, have given us no problem touch wood.
Originally i am from Nairobi East Africa and my family have been involved in the safari rally for many years.
My question is, since coming to the UK, i have heard so many things about bottom ends knocking and shocking stories.
This was completely new to me and my family as back in Kenya, we use to thrash the Subaru's, whether they were brats, legacys, imprezas or even Leons. Even in the rallying days, they use to all be throwed around like a toy. Never once did an engine knock.
We came here and discovered that subarus dont seem to be very bullet proof in the UK.
Could some one please explain why do boxer engines in subarus knock?
I have heard silly things like going around corners fast can cause it to knock? oil pressure problems? poor detonation? group n sumps fix? etc. etc. etc.
Surely these engines should be bullet proof? as far as i know..
It does bother me knowing that engines here are so weak.
Any knowledge would be very helpful.
My family have owned many subaru's in the past and i currently own a classic in pristine condition sitting on Rota Formula Mesh.
All our Subaru's we have had, have given us no problem touch wood.
Originally i am from Nairobi East Africa and my family have been involved in the safari rally for many years.
My question is, since coming to the UK, i have heard so many things about bottom ends knocking and shocking stories.
This was completely new to me and my family as back in Kenya, we use to thrash the Subaru's, whether they were brats, legacys, imprezas or even Leons. Even in the rallying days, they use to all be throwed around like a toy. Never once did an engine knock.
We came here and discovered that subarus dont seem to be very bullet proof in the UK.
Could some one please explain why do boxer engines in subarus knock?
I have heard silly things like going around corners fast can cause it to knock? oil pressure problems? poor detonation? group n sumps fix? etc. etc. etc.
Surely these engines should be bullet proof? as far as i know..
It does bother me knowing that engines here are so weak.
Any knowledge would be very helpful.
02 November 2016, 01:22 PM
#2
They are bullet proof when kept within design parameters and properly maintained (and driven with a degree of mechanical sympathy).
Less so when you start increasing the boost & power (outside design parameters). Add in poor aftermarket parts, poor builds, poor maps and poor maintenance and you can expect issues.
Less so when you start increasing the boost & power (outside design parameters). Add in poor aftermarket parts, poor builds, poor maps and poor maintenance and you can expect issues.
02 November 2016, 01:29 PM
#3
Well maintained a Subaru 2ltr is a great engine. Not so the miserable 2.5 that has suffered so many failures, mostly from broken pistons that usually take out the entire engine. Subaru has failed to address this problem and consequently has earned a poor reputation and has lost so much good will and custom.
02 November 2016, 01:29 PM
#4
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I agree 100% BUT i have heard people that have bought brand new sti's etc. and have done 35k etc. and still knock? without any modification? unless of course they push it to hard standard which i can understand is taking it out of the parameters.
But then again even back home you would over rev the car and that engine would be still bullet proof. I remember thrashing a leon (standard) and it never died. Rust killed the car but the engine was bullet proof...
But then again even back home you would over rev the car and that engine would be still bullet proof. I remember thrashing a leon (standard) and it never died. Rust killed the car but the engine was bullet proof...
02 November 2016, 01:32 PM
#5
For me I'd say its poor servicing, I've owned a few non turbo Impreza's and all been bullet proof, even if haven't been looked after amazingly, but with the turbo models they need regular servicing, as the engines under a lot of stress. I've had 2 turbo models and no problems to date.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
02 November 2016, 01:34 PM
#6
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I agree 100% BUT i have heard people that have bought brand new sti's etc. and have done 35k etc. and still knock? without any modification? unless of course they push it to hard standard which i can understand is taking it out of the parameters.
But then again even back home you would over rev the car and that engine would be still bullet proof. I remember thrashing a leon (standard) and it never died. Rust killed the car but the engine was bullet proof...
But then again even back home you would over rev the car and that engine would be still bullet proof. I remember thrashing a leon (standard) and it never died. Rust killed the car but the engine was bullet proof...
My classic engine has died recently but like others have mentioned it was pushing them out of their designed parameters. I was running well over the standard BHP.
Another factor could be the weather or the cold starts but also don't forget how old the classic is now.
02 November 2016, 01:38 PM
#7
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For me I'd say its poor servicing, I've owned a few non turbo Impreza's and all been bullet proof, even if haven't been looked after amazingly, but with the turbo models they need regular servicing, as the engines under a lot of stress. I've had 2 turbo models and no problems to date.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
I mean causing a big end failure is not that easy. With my previous experience, there use to be times when we never even use to change the oil and still it wouldn't want to die.
As mentioned above, i believe the weather could be a big part of it in this country.
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02 November 2016, 01:42 PM
#8
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Yep seems to be the 2.5ltr Hatch engines which were caused by the bad factory map. A lot of corners were cut to meet both cost and EU regulations.
My classic engine has died recently but like others have mentioned it was pushing them out of their designed parameters. I was running well over the standard BHP.
Another factor could be the weather or the cold starts but also don't forget how old the classic is now.
My classic engine has died recently but like others have mentioned it was pushing them out of their designed parameters. I was running well over the standard BHP.
Another factor could be the weather or the cold starts but also don't forget how old the classic is now.
02 November 2016, 01:44 PM
#9
I was speaking to a guy who use to break Impreza's he said he bought a JDM classic with a closed deck engine, and spent weeks trying to blow the engine and couldn't 
Why he was trying it don't know. So depends if they had JDM engines aswell, another factor could be the heat, a lot of cold starts won't help, that might be a factor.
Why he was trying it don't know. So depends if they had JDM engines aswell, another factor could be the heat, a lot of cold starts won't help, that might be a factor.
I have also found that a lot of people dont maintain there cars in this country, you are right, but i mean, should this really still cause an engine to knock? If its been maintained poorly.
I mean causing a big end failure is not that easy. With my previous experience, there use to be times when we never even use to change the oil and still it wouldn't want to die.
As mentioned above, i believe the weather could be a big part of it in this country.
I mean causing a big end failure is not that easy. With my previous experience, there use to be times when we never even use to change the oil and still it wouldn't want to die.
As mentioned above, i believe the weather could be a big part of it in this country.
02 November 2016, 01:48 PM
#11
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Thread Starter
For me I'd say its poor servicing, I've owned a few non turbo Impreza's and all been bullet proof, even if haven't been looked after amazingly, but with the turbo models they need regular servicing, as the engines under a lot of stress. I've had 2 turbo models and no problems to date.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
What I've found in the UK is a lot of poorly maintained cars about, that most likely get thrashed a lot. And poorly modified.Went with my mate to look at some and they were so many poor examples, one you could tell had been poorly looked after, another one had no oil, even the one he bought hadn't been serviced amazingly but was owned by an old bloke with one previous owner.
02 November 2016, 01:51 PM
#12
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Thread Starter
I was speaking to a guy who use to break Impreza's he said he bought a JDM classic with a closed deck engine, and spent weeks trying to blow the engine and couldn't
Why he was trying it don't know. So depends if they had JDM engines aswell, another factor could be the heat, a lot of cold starts won't help, that might be a factor.
Why he was trying it don't know. So depends if they had JDM engines aswell, another factor could be the heat, a lot of cold starts won't help, that might be a factor.
If so, then that probably explains why we never use to have problems.
But are JDM engines just stronger i.e better built? quality of material?
02 November 2016, 02:04 PM
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Yep seems to be the 2.5ltr Hatch engines which were caused by the bad factory map. A lot of corners were cut to meet both cost and EU regulations.
My classic engine has died recently but like others have mentioned it was pushing them out of their designed parameters. I was running well over the standard BHP.
Another factor could be the weather or the cold starts but also don't forget how old the classic is now.
My classic engine has died recently but like others have mentioned it was pushing them out of their designed parameters. I was running well over the standard BHP.
Another factor could be the weather or the cold starts but also don't forget how old the classic is now.
Mapped or unmapped, standard or modded, low or high miles they still fail. Some people have had multiple engines from subaru that keep failing time after time.
You'll notice very few specialist rebuilt ones (assuming a decent builder of course) fail.
02 November 2016, 02:10 PM
#14
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Sorry but that's rubbish, all the 2.5's from 05 hawk wrx to the new sti are suffering higher counts of failures than typical for an OEM engine. Little has changed on the engine itself.
Mapped or unmapped, standard or modded, low or high miles they still fail. Some people have had multiple engines from subaru that keep failing time after time.
You'll notice very few specialist rebuilt ones (assuming a decent builder of course) fail.
Mapped or unmapped, standard or modded, low or high miles they still fail. Some people have had multiple engines from subaru that keep failing time after time.
You'll notice very few specialist rebuilt ones (assuming a decent builder of course) fail.
As far as im aware they were bullet proof. Im taking about classics, brats leones imprezas and foresters, no new age stuff..
02 November 2016, 02:15 PM
#15
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Sorry but that's rubbish, all the 2.5's from 05 hawk wrx to the new sti are suffering higher counts of failures than typical for an OEM engine. Little has changed on the engine itself.
Mapped or unmapped, standard or modded, low or high miles they still fail. Some people have had multiple engines from subaru that keep failing time after time.
You'll notice very few specialist rebuilt ones (assuming a decent builder of course) fail.
Mapped or unmapped, standard or modded, low or high miles they still fail. Some people have had multiple engines from subaru that keep failing time after time.
You'll notice very few specialist rebuilt ones (assuming a decent builder of course) fail.
Its not rubbish
Do a quick search and you will see the early hatch 2.5s had a much higher failure rate and it was much earlier on. Yes the hawks also had problems but it was more evident with the hatch and Subaru also offered a rom flash. If you look at the buying threads where people ask what they need to check when looking at the car you will clearly see people mention checking the service history to see if it has had the rom flash or remapped.
Do you know why they had the 2.5 in the EU market. It was to meet the new EU regulations. Why weren't they forged or closed decked it was because of cost.
Now tell me I'm talking rubbish
My previous post was regarding the 2.5s and didn't focus on the 2ltr engines
02 November 2016, 02:47 PM
#16
Well that one he was talking about had a closed deck engine which I believe has forge internals from factor, some JDM models did. I'm sure someone else can add to this.
Originally Posted by KOEScoob
Thats a point there, whether they are JDM engines i dont know. I could raise this back home and find out.
If so, then that probably explains why we never use to have problems.
But are JDM engines just stronger i.e better built? quality of material?
If so, then that probably explains why we never use to have problems.
But are JDM engines just stronger i.e better built? quality of material?
02 November 2016, 02:50 PM
#17
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these are the factors that could cause bottom end? Am i correct..
02 November 2016, 02:52 PM
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Its not rubbish
Do a quick search and you will see the early hatch 2.5s had a much higher failure rate and it was much earlier on. Yes the hawks also had problems but it was more evident with the hatch and Subaru also offered a rom flash. If you look at the buying threads where people ask what they need to check when looking at the car you will clearly see people mention checking the service history to see if it has had the rom flash or remapped.
Do you know why they had the 2.5 in the EU market. It was to meet the new EU regulations. Why weren't they forged or closed decked it was because of cost.
Now tell me I'm talking rubbish
My previous post was regarding the 2.5s and didn't focus on the 2ltr engines
Do a quick search and you will see the early hatch 2.5s had a much higher failure rate and it was much earlier on. Yes the hawks also had problems but it was more evident with the hatch and Subaru also offered a rom flash. If you look at the buying threads where people ask what they need to check when looking at the car you will clearly see people mention checking the service history to see if it has had the rom flash or remapped.
Do you know why they had the 2.5 in the EU market. It was to meet the new EU regulations. Why weren't they forged or closed decked it was because of cost.
Now tell me I'm talking rubbish
My previous post was regarding the 2.5s and didn't focus on the 2ltr engines
Do you not think that when the engines failed the first thing subaru would do on the new ones is flash the map?
Also you seem to have forgotten 330's are failing as well as normal sti's, they are totally different maps. A more mild map will help protect a weakness, no mater what the weakness is.
Strip the engine down and compare and you will find little to no difference.
02 November 2016, 03:02 PM
#20
I'm just guessing I could be wrong. But those who regularly service there cars on here and don't abuse them have high mile cars. Weather might be playing a factor. Plus euro engines might not be built to the sand standards, although I've heard of JDM engines with knocking issues.
Did all these cars have turbo's?
Did all these cars have turbo's?
Originally Posted by KOEScoob
So at the end of the day it could either be, poor servicing, or the fact that UK engines were not as strong as the JDMs or being over driven outside its parameter...
these are the factors that could cause bottom end? Am i correct..
these are the factors that could cause bottom end? Am i correct..
02 November 2016, 03:02 PM
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02 November 2016, 03:06 PM
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I'm just guessing I could be wrong. But those who regularly service there cars on here and don't abuse them have high mile cars. Weather might be playing a factor. Plus euro engines might not be built to the sand standards, although I've heard of JDM engines with knocking issues.
Did all these cars have turbo's?
Did all these cars have turbo's?
02 November 2016, 03:10 PM
#24
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It had from what I can tell a UK2000 engine so the 218bhp variant. When I finished with it was running well over a newage STI would be. What I didn't expect was that I would be made redundant so the scooby has been parked up.
Most of the components were at their limit . But hey boost is life jk.
02 November 2016, 03:22 PM
#25
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I'm yet to see anything that shows a like for like on figures (as in failure per 1000 cars), sales have plummeted since the hawk so there are far less units out their, so therefor will be less failures in more recent ones.
Do you not think that when the engines failed the first thing subaru would do on the new ones is flash the map?
Also you seem to have forgotten 330's are failing as well as normal sti's, they are totally different maps. A more mild map will help protect a weakness, no mater what the weakness is.
Strip the engine down and compare and you will find little to no difference.
Do you not think that when the engines failed the first thing subaru would do on the new ones is flash the map?
Also you seem to have forgotten 330's are failing as well as normal sti's, they are totally different maps. A more mild map will help protect a weakness, no mater what the weakness is.
Strip the engine down and compare and you will find little to no difference.
The main issue is ring land failure which is caused by both parts and maps. There are differences in the engines themselves
I'm not going all keyboard warrior on you so chill
02 November 2016, 03:32 PM
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Not quite because the 320 package (99% sure it was offered on the hatch and the saloon) that was offered came out quite a bit later. Also it doesn't work on the basis of as soon as one engine goes lets issue a full new flash. There is development and based on how Subaru UK handled it they kept brushing it under the carpet. The failure rate of hawk vs hatch is massive and they often say if you are going 2.5 stock then avoid early hatches.
The main issue is ring land failure which is caused by both parts and maps. There are differences in the engines themselves
I'm not going all keyboard warrior on you so chill
The main issue is ring land failure which is caused by both parts and maps. There are differences in the engines themselves
I'm not going all keyboard warrior on you so chill
Sorry didnt mean to come across has having a go.
Tthe whole issue is there isn't a single cause. They failed post map flash and pre map flash. I think they tried to save soo much cost to build they built in too many weak points.
02 November 2016, 03:45 PM
#27
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02 November 2016, 03:49 PM
#28
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Now I'm not too sure on this so please take it with a pinch of salt but the 2.5 isn't a completely different block. Easiest way to explain it in a really simple way is its a 2lt re-bored and not a completely new design. When it was released they quickly found it could only be pushed so far with the stock internals. I think it was Cosworth who realised the potential of the block and how much torque you could get out of them.
In terms of rebuilding though when the pistons crack in quite a few the actual block itself has cracked. People then rebuild them without realising causing the engine to blow quite quickly.
02 November 2016, 05:39 PM
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Thats why I said it mate it occurred to me you might have taken what I said the wrong way and in all honesty didn't want to start an argument
Now I'm not too sure on this so please take it with a pinch of salt but the 2.5 isn't a completely different block. Easiest way to explain it in a really simple way is its a 2lt re-bored and not a completely new design. When it was released they quickly found it could only be pushed so far with the stock internals. I think it was Cosworth who realised the potential of the block and how much torque you could get out of them.
In terms of rebuilding though when the pistons crack in quite a few the actual block itself has cracked. People then rebuild them without realising causing the engine to blow quite quickly.
Now I'm not too sure on this so please take it with a pinch of salt but the 2.5 isn't a completely different block. Easiest way to explain it in a really simple way is its a 2lt re-bored and not a completely new design. When it was released they quickly found it could only be pushed so far with the stock internals. I think it was Cosworth who realised the potential of the block and how much torque you could get out of them.
In terms of rebuilding though when the pistons crack in quite a few the actual block itself has cracked. People then rebuild them without realising causing the engine to blow quite quickly.