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If the goal is to reduce the time of car being off the road, avoid surprises when travelling long distances and save some money in long term, changing both in one go is more logical.

for these manifolds I am not convinced if the crack is because of material failure under stress or malfunction of a sensor or mechanism that increases boost to a point that manifold cracks (which seems to be the reason mine failed). First reason means second side will fail, sooner or later. Second reason means if you find and resolve the issue it will not happen and you can leave the repair for later.

This a judgment each owner can make for the car considering the situation and the consequences of part failure on their plans. Generally engineers tend to replace all risky parts when the equipment is down for maintenance. For others it might be a second car for weekends and they go down the other route. Bear in mind when this particular item fails, car is still usable but engine is under powered for acceleration.
 

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I’m sorry, but I don’t understand the logic in changing something that works and is doing what it’s supposed to do.
Serviceable items are things like oil, filters, tyres, etc
Using your way of thinking, folk would be changing bulbs because they might break, exhausts because they might leak, etc
These modern type manifolds are going to be perfectly fine for the life of the car in the vast majority of cars on the road. In your case, I think you were just unlucky, or the crack in the other manifold was’nt picked up with the other side at the time - which sounds likely
The logic is that items have a 'life'. Some items are more critical that others.

If you were to take the timing chains for example - and just leave them until they break, the resultant aftermath is going to cost you not just a new set of chains, but most likely a new engine.

Preventitive maintenance allows you to choose the timing of change out, prevents un-necessary damage to other compenents, allows you time to put aside the finances for the change.


Things like Filters need changed regulary because they become blocked - engine oil filter - block that, with no bypass - and you're going to have another engine change out.
Bulbs and exhausts are ease of access items with little in the way to affect other things if they break or fail.. Tyres and brakes are critical items though and should certainly be changed before they fail. I don't fancy ending up in a crash because I waited until my tyres failed - why else would the govt put out laws with minimum tread?

You are welcome to your way of thinking, but using my experience at work both aviation and offshore, seeing how preventitive maintenance is more benefical in the long term tas opposed to run til it breaks maintenance - I'll stick to being pro-active. It might cost me a bit more in the long run, but I know that my car will be running better for it - with little to no chance of breakdown.
 
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The logic is that items have a 'life'. Some items are more critical that others.

If you were to take the timing chains for example - and just leave them until they break, the resultant aftermath is going to cost you not just a new set of chains, but most likely a new engine.

Preventitive maintenance allows you to choose the timing of change out, prevents un-necessary damage to other compenents, allows you time to put aside the finances for the change.


Things like Filters need changed regulary because they become blocked - engine oil filter - block that, with no bypass - and you're going to have another engine change out.
Bulbs and exhausts are ease of access items with little in the way to affect other things if they break or fail.. Tyres and brakes are critical items though and should certainly be changed before they fail. I don't fancy ending up in a crash because I waited until my tyres failed - why else would the govt put out laws with minimum tread?

You are welcome to your way of thinking, but using my experience at work both aviation and offshore, seeing how preventitive maintenance is more benefical in the long term tas opposed to run til it breaks maintenance - I'll stick to being pro-active. It might cost me a bit more in the long run, but I know that my car will be running better for it - with little to no chance of breakdown.
Totally and completely right
 

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Fair enough, but the example you chose, the timing belt/ chain is a serviceable part! If I’m right, it’s 10 years or 150000 miles
Of course you do brakes if they’re kaput, modern cars tell you nowadays.
All I’m trying to say is the inlet manifold isn’t a serviceable part
And, I think you should touch wood before saying little or no chance of breaking down...
 

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Ps...
I’m also in the maintenance game
I’ve been servicing and repairing forklift trucks for the past 35 years
What a laugh that is...
 

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It's not a service item, no. But it is an item that we have seen fail time and time again to know its worth changing both if you're going to the effort of doing one.
 

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You don’t see them failing time and again, you only see them failing on forums.
Generally, people only write into these forums because they’ve got a gripe.
Jag have built 1000’s of cars with plastic manifolds and how many fail? I bet it’s a tiny percentage
You’ve got to remember that everything’s got a potential to break, generally doesn’t.
How many folks out there have changed their windscreen washer pump which has a potential to cause very, very expensive damage, but haven’t?
 

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I think there is a difference between doing something for the sake of it, and changing something that may be an issue while the car is stripped already. Which is the point we are making. This is why we change the water pump with the timing belt.
 

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You don’t see them failing time and again, you only see them failing on forums.
Generally, people only write into these forums because they’ve got a gripe.
Jag have built 1000’s of cars with plastic manifolds and how many fail? I bet it’s a tiny percentage
You’ve got to remember that everything’s got a potential to break, generally doesn’t.
How many folks out there have changed their windscreen washer pump which has a potential to cause very, very expensive damage, but haven’t?
The simple fact that one side has failed suggests that both covers were manufactured at a time when the materials used or the design was inadequate for the job. It's a labour intensive job to get to the covers, so having spent £800 to get in there, it makes sense to me to spend an extra £200 & do both covers.
 

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And now that we are seeing blocked MAP sensors, I wonder if there is a link between those and cracked manifolds?
Certainly I would add MAP sensor cleaning to a service schedule.
 
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For parts, you can save some money. I bought both sides for £90 and was impressed with quality and packing.

I did both sides over weekend. Took me 16hr but I could save probably 5-6hours if did try to clean the hard to reach areas. If I do it second time it should take 8hrs. Doing both sides won’t save a huge amount of time. Maybe 1hr for a professional because:
-there is high pressure fuel line from left rail to right. If you do both sides, that move be free to move and save a lot of hassle.
-you have to remove throttle body for RH side which can save some time to do LH.
-secondary bulk head panel (under the windscreen) has to be removed for any side.

according to WM you have to move EGRs, drain coolant (that needs removal of under body and jacking the car up), remove air intake ducts, move turbo bypass valve, remove accessories drive belt, timing belt cover and many other steps that are “not“ needed at all. Those steps will not increase the quality of repair, increase repair time significantly and might cause other problems due to human error. I won’t be surprise if you find the garage that will do this repair for less than £500.
I can confirm what hamed wrote. It took my mechanic (Indy) 7 hours for the drivers side cover. He will do the other side in 2 weeks. He stated he only looses half an hour if he does it in two sessions and not both sides at once. I bought the parts with the help of hamed in the UK for 220 EUR both sides including taxes and shipment to Germany. My mechanic charges me 460 EUR for one side. My local Cat-dealer ..... 1700 EUR for each side including material.... :)...
And yes, I do the other side because I want to. Not because it is damaged. I also prefer acting rather than reacting :) .
My cracked cover. You could see the crack easily after cleaning.

182328


Before changing:

182329
 

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And now that we are seeing blocked MAP sensors, I wonder if there is a link between those and cracked manifolds?
Certainly I would add MAP sensor cleaning to a service schedule.
Especially as it is so easily accessible. It's now going to be part of my oil change routine.
 

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I read about the map sensor and I am already paranoid about the cracked manifolds so I cleaned my MAP sensor this weekend, other than some gunk in the middle it was spotless. The car has done 136000 miles. Does anyone know if you can get MAP sensor readings on Torque?
 

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I read about the map sensor and I am already paranoid about the cracked manifolds so I cleaned my MAP sensor this weekend, other than some gunk in the middle it was spotless. The car has done 136000 miles. Does anyone know if you can get MAP sensor readings on Torque?
I am sure you can. If not try a free app on iPhone called “car scanner”. I am about to conclude that checking bypass valve and primary turbo arm movement should be on the list of preventative measures. However, those are not an easy DIY. Anyhow, MAP readings will show if there is problem before starting checks.
 

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I am sure you can. If not try a free app on iPhone called “car scanner”. I am about to conclude that checking bypass valve and primary turbo arm movement should be on the list of preventative measures. However, those are not an easy DIY. Anyhow, MAP readings will show if there is problem before starting checks.
I'm sure you posted it somewhere but would you be able to reiterate the readings one should be looking for? I think you mentioned something about full throttle was 255 but may read up to 300, but I'm sure there was more you posted?
 

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I'm sure you posted it somewhere but would you be able to reiterate the readings one should be looking for? I think you mentioned something about full throttle was 255 but may read up to 300, but I'm sure there was more you posted?
At idle with warm engine,
MAP: atmosphere pressure (90-110kpa)
Boost: 40-60kpa.

on full throttle I was reading 255 flat peak for MAP that seems to be saturation point of the MAP sensor. Not sure if it should be allowed to reach 255.
 

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What is the unit? psi? If yes that’s about right. Slightly higher than mine which is 36psi
100000 Pascals = 1bar pressure = 14.7Psi.

Think sockpet means his boost was 40Kpa - about 0.4bar or 6.8Psi.

40Psi would be a 2.5bar boost. A tad high, no?
 
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