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Discussion Starter #1
Hello bmw community I recently did a coolant diagnostic test to check where the coolant was leaking from . They told me the car was losing 5 psi after a few mins . The perform a combustion leak test and it came out that the car has a small head gasket leak . What should I do should I replace the head gasket or get another engine or rebuild the engine completely?


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I usually like to see the color change more significantly. Was the C.O. gases test (above) performed on a cold, warm or hot engine? Usually worst hot.

Are you/they 101% sure there are NO OTHER leaks, leading to the loss of cooling system pressure?

Lastly I cannot give an opinion owing to not knowing the engine, mileage, age & condition of the engine.
Do they have the capability to timesert the block? Are they even familiar with such?
 

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Discussion Starter #6
I usually like to see the color change more significantly. Was the C.O. gases test (above) performed on a cold, warm or hot engine? Usually worst hot.

Are you/they 101% sure there are NO OTHER leaks, leading to the loss of cooling system pressure?

Lastly I cannot give an opinion owing to not knowing the engine, mileage, age & condition of the engine.
Do they have the capability to timesert the block? Are they even familiar with such?
Yea that what I said he said it’s very small and they could find a leak anywhere else . But I have seen a leak on the ground every time the car is turn on . Or it’s turn off . I believe it was warm or hot because I drove it there to get it there . It warmed up all the way to operating temperature. They waited like 20 min then they started to test for leaks . They pressured test it and found no external leak (even tho it’s leaking on the ground .then they noted that it was losing 5 psi after a few minute so they started the combustion test . After they told me it has head gasket leak but it’s not bad right . Because the car run perfectly no misfires . The engine is M54B25 . The car is at 176000 mile but the engine was replaced by other one from LKQ the replacement engine has 80000 miles . The car is a 2001 bmw 325i . Engine run perfectly no misfires gets up an go .
What’s do you mean by timesert the block.( I believe they could because they are a professional German auto repair shop ) . Not sure tho .



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I would drive it until it starts showing problems, keeping a very close eye on the coolant temperature.
We’ve seen some HG leaks be undetected for a while allowing you to decide what to do about it and when.

If you plan to keep the car long term, an M54B30 swap can be done when you’re ready. It is plug-and-play, assuming the engines are similar production dates. You’d want a complete engine. The B30 air box, MAF, intake boots, and throttle body are larger, so you need those. The exhaust, transmision, wiring harnesses, etc. are the same.
 

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Discussion Starter #9
I would drive it until it starts showing problems, keeping a very close eye on the coolant temperature.
We’ve seen some HG leaks be undetected for a while allowing you to decide what to do about it and when.

If you plan to keep the car long term, an M54B30 swap can be done when you’re ready. It is plug-and-play, assuming the engines are similar production dates. You’d want a complete engine. The B30 air box, MAF, intake boots, and throttle body are larger, so you need those. The exhaust, transmision, wiring harnesses, etc. are the same.
Right now it’s right smack in the middle the temperature no milky on the cap of the oil . I do plan to keep the car really since I put so much money into it .Does the M54 B30 have any problems . I have heard of oil consumption.
How about diff?


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Right now it’s right smack in the middle the temperature no milky on the cap of the oil . I do plan to keep the car really since I put so much money into it .Does the M54 B30 have any problems . I have heard of oil consumption.
How about diff?
You cannot go by the temperature gauge on the dashboard. It lies! You’ll need to either use the cluster test to view it or an app like OBD Fusion to monitor/log it.

B30 is more likely to burn oil because of oil rings, some do, some don’t. If you’re swapping engines it’s a +40HP no brainer IMO.
Otherwise, B25 and B30 have the same issues.

The AT and Diff have slightly higher ratios on the 325 vs 330.
That makes a B30-swapped 325 faster than a 330, which is nice. I have one and like it.
 

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Discussion Starter #12
You cannot go by the temperature gauge on the dashboard. It lies! You’ll need to either use the cluster test to view it or an app like OBD Fusion to monitor/log it.

B30 is more likely to burn oil because of oil rings, some do, some don’t. If you’re swapping engines it’s a +40HP no brainer IMO.
Otherwise, B25 and B30 have the same issues.

The AT and Diff have slightly higher ratios on the 325 vs 330.
That makes a B30-swapped 325 faster than a 330, which is nice. I have one and like it.
For real not good . Do I check it when all the way up to operating temp? Also what the normal operating range ? Can d oil ring be replaced with better one ? Do they also have same driveshaft ecu?



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If you use the right oils, drive it regularly, keep the CCV system in check and properly maintain the car, the rings (low tension) usually stay compliant.
 

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In my experience, yes.
We've rescued a couple also that had been neglected also with chemical intervention and aggressive oil changes.
But the issue is a two horse cart.

1) Malfunctioning CCV systems can attribute to oil burning by means of introducing oil into the combustion chamber by way of the intake manifold.
2) Sticking oil control rings can also do the same, albeit by leaving oily film that didn't get wiped clean on the downstroke.

The symptoms are the same for both. Oil gets introduced into the combustion chamber, and let go long enough it can have a devastating effect on the cats. Obviously the fix for either is different.
Most usually one replaces the entire CCV system and see if there's enough of an improvement. If not and if you think there's more to be had, the rings need cleaning (carefully) with the right chemicals.

Some cars have one of the above, others have both. Largely depends on the total history of the car.
Usually the first owner with a lease is the biggest culprit.
 

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A couple of things on this....
With the loss you are seeing, I would like to suggest you could be looking at a cracked head. The job is pretty much the same as a head gasket, but if you do not inspect for the head AND replace the gasket, you can come out the other side of the job still having a leak. Typically the wall between a water galley and an exhaust valve will crack. The wall in question is going to be 2 or 3 mm thick, and when it leaks the coolant will dribble directly into the exhaust port. Google, BMW M52 HEAD CRACKED, then choose Images. You will see what to look for and where to look. The M52 and the M50 crack the same way, by the way. You have the M52, so you only care about the M50 as a point of reference.

As for the timeserts, these should not be needed if you have an M52 (323 or 328) engine with a cast iron block. The M54 (325 or 330) has the aluminum block. One thing that is important is to use new head bolts. Take the old bolts out and throw them away. Head bolts have a "stretch quality" to them and the old ones do not stretch properly when you put them back in.
 

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As for the timeserts, these should not be needed if you have an M52 (323 or 328) engine with a cast iron block. The M54 (325 or 330) has the aluminum block.
M52TU is aluminum like the M54, not cast iron.
You’re thinking of the M50 cast iron block?
 

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Discussion Starter #18
A couple of things on this....
With the loss you are seeing, I would like to suggest you could be looking at a cracked head. The job is pretty much the same as a head gasket, but if you do not inspect for the head AND replace the gasket, you can come out the other side of the job still having a leak. Typically the wall between a water galley and an exhaust valve will crack. The wall in question is going to be 2 or 3 mm thick, and when it leaks the coolant will dribble directly into the exhaust port. Google, BMW M52 HEAD CRACKED, then choose Images. You will see what to look for and where to look. The M52 and the M50 crack the same way, by the way. You have the M52, so you only care about the M50 as a point of reference.

As for the timeserts, these should not be needed if you have an M52 (323 or 328) engine with a cast iron block. The M54 (325 or 330) has the aluminum block. One thing that is important is to use new head bolts. Take the old bolts out and throw them away. Head bolts have a "stretch quality" to them and the old ones do not stretch properly when you put them back in.
Not good should I just take to a professional shop and fix it at that price ? They are going to check the head and if it’s need resurface they will resurface it
Is it better to get the used engine of the head gasket? I am thinking because although it’s cheaper to buy a engine used it can still with a head gasket like this one did


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M52TU is aluminum like the M54, not cast iron.
You’re thinking of the M50 cast iron block?

Sorry to sound like I'm arguing the point, but the North American Market got the M52 with a cast iron block, except in the Z3.

"In most markets, the M52 switched from the M50's cast iron engine block to a lightweight aluminium engine block. However, in the United States and Canada, some cars (not including the Z3) retained the M50's cast iron engine block,[3][4] while other cars used the new aluminum M52 block with iron sleeves.[3]"
 

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Not good should I just take to a professional shop and fix it at that price ? They are going to check the head and if it’s need resurface they will resurface it
Is it better to get the used engine of the head gasket? I am thinking because although it’s cheaper to buy a engine used it can still with a head gasket like this one did
If you can do the head gasket, then you can also do the head. It's not that big of a deal. A welder who can weld aluminum can easily fix the crack.

But BEFORE you wig out about this, pull the head and inspect it. My point was about inspection, if you do not inspect then the new gasket will be a waste of time and money. My car had a cracked head for more than 6 months, and I discovered it because the cylinder filled with coolant one weekend, and when I went to start my car for work on Monday morning, it hydrolocked. I pulled the plugs and it squirted coolant out of #3 cylinder. If I knew then what I know now, I could have put the plugs back in and gone to work and scheduled the service in a less hectic manner, and possibly saved some money. I was going to buy a blank head, but that required moving the valve train from the old head to the new one. I found a place that sold a complete head with the crack repaired for less than a new blank from BMW.
 
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