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Old 01-05-2017, 04:12 PM   #1
CanadianDirty30
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Headgasket vs engine swap

Well the time has finally come, as I was replacing my upper and lower oil pan gaskets I noticed a thin coating of oil and coolant mixture at the bottom of my lower pan. Due to the small amount of residue I'm thinking the headgasket leak is very small but still about to go in the foreseeable future , which I was expecting at some point.

This raises a decision to make. Is it worth my time tearing down my m42 which is at nearly 300,000kms, putting time and money into replacing the HG and other "while you're in there" parts on such i high mileage engine. Or would it be a better option to just put a similar amount of time and money into an engine swap such as an m20, lower Km m42, m50, etc..

I just wanted other opinions on the situation. Keep in mind I would like to stay within the same dollar figure as replacing a headgasket and other parts if I were to swap. Any opinions will be helpful!
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Old 01-05-2017, 04:17 PM   #2
berlow94
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Quote:
Originally Posted by CanadianDirty30 View Post
Well the time has finally come, as I was replacing my upper and lower oil pan gaskets I noticed a thin coating of oil and coolant mixture at the bottom of my lower pan. Due to the small amount of residue I'm thinking the headgasket leak is very small but still about to go in the foreseeable future , which I was expecting at some point.



This raises a decision to make. Is it worth my time tearing down my m42 which is at nearly 300,000kms, putting time and money into replacing the HG and other "while you're in there" parts on such i high mileage engine. Or would it be a better option to just put a similar amount of time and money into an engine swap such as an m20, lower Km m42, m50, etc..



I just wanted other opinions on the situation. Keep in mind I would like to stay within the same dollar figure as replacing a headgasket and other parts if I were to swap. Any opinions will be helpful!


If you're doing the work yourself and your only cost is parts, I'd say go for a swap!

It might be twice the amount of work as just replacing the head gasket, but if the cost of parts are the same then you can look at it as gaining experience!

With the being said, I can assure you that the cost of "while you're in there" parts for a swap is twice as much as the head gasket job.


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Old 01-05-2017, 04:23 PM   #3
ForcedFirebird
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Might just be a profile gasket, pretty simple compared to a HG on an m42.
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Old 01-05-2017, 05:03 PM   #4
CanadianDirty30
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Originally Posted by berlow94 View Post
If you're doing the work yourself and your only cost is parts, I'd say go for a swap!

It might be twice the amount of work as just replacing the head gasket, but if the cost of parts are the same then you can look at it as gaining experience!

With the being said, I can assure you that the cost of "while you're in there" parts for a swap is twice as much as the head gasket job.


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Yes that's my main reason I would lean towards a swap, if it were a similar cost! It would require some looking around for what I need at a good price though. But yea while you're in there parts really start to add up, I'd be conservative with what I replace depending on importance and the condition of certain things

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Might just be a profile gasket, pretty simple compared to a HG on an m42.
Alright I'll check that out for sure first then! Any way to diagnose between the two before tearing the engine down possibly? Or is that the type of thing I gotta see for myself once I'm in there
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Old 01-05-2017, 05:15 PM   #5
ForcedFirebird
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You can attempt a pressure test, but since it's going in your oil, hard to tell if it's HG or profile (see below).

You do know that your oil naturally collects condensation from your engine (specially in winter months)? The moisture will go to the bottom of your oil? I see you are in CAN and it is early Jan, so this might just be the case.

Think of it like this: Your favorite beverage in a can was taken from the fridge. You put that can on the table on a warm summer day and you see the can get moist. Well, this same thing happens to the inside walls of your engine when you shit it off on a cool day, only in reverse. The inside of your engine will have that same "sweat" build up inside when it is shut off on a cool/cold day. Oil is lighter than water, so it will sink to the bottom.

So, best way to diagnose is to let your engine run up to full temp (this will "burn off any water residue), then immediately drain your oil and leave the drain plug out. Let it sit until completely cool. Pour a little fresh oil in (1/2-1qt) with the plug open to flush out any residual moisture. Then pressurize your cooling system with the plug open and see if coolant does in fact drip out of your drain plug.

When you engine is fresh turned off and the dip stick pulled, is the oil milk-shake-like?
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Old 01-05-2017, 07:44 PM   #6
CanadianDirty30
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Originally Posted by ForcedFirebird View Post
You can attempt a pressure test, but since it's going in your oil, hard to tell if it's HG or profile (see below).

You do know that your oil naturally collects condensation from your engine (specially in winter months)? The moisture will go to the bottom of your oil? I see you are in CAN and it is early Jan, so this might just be the case.

Think of it like this: Your favorite beverage in a can was taken from the fridge. You put that can on the table on a warm summer day and you see the can get moist. Well, this same thing happens to the inside walls of your engine when you shit it off on a cool day, only in reverse. The inside of your engine will have that same "sweat" build up inside when it is shut off on a cool/cold day. Oil is lighter than water, so it will sink to the bottom.

So, best way to diagnose is to let your engine run up to full temp (this will "burn off any water residue), then immediately drain your oil and leave the drain plug out. Let it sit until completely cool. Pour a little fresh oil in (1/2-1qt) with the plug open to flush out any residual moisture. Then pressurize your cooling system with the plug open and see if coolant does in fact drip out of your drain plug.

When you engine is fresh turned off and the dip stick pulled, is the oil milk-shake-like?
You couldn't have explained that any better! Yea where I live in Canada has been pretty cold lately so there's most likely moisture in the engine. I'll definitely give this a try as soon as I can. So if I go through all these steps and coolant drips out the drain plug , would that be a sign of the headgasket as opposed to the profile gasket?
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Old 01-06-2017, 07:11 AM   #7
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300,000km is not really super high mileage. I guess it is for you guys up there but here in texas, that is low miles for the year vehicle you have. my 91 318 had 250k mile on it when I sold it in 08. I bought it with 220k miles on it but I didn't like the m42 engine so that's why I got rid of it.

its like the m20, in how long it will last.
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Old 01-06-2017, 07:43 AM   #8
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I wouldn't swap it, at least not without keeping the original engine stored away in the garage.

E30s are not POS disposable econo cars. They are well built, well engineering machines from a high point in German auto manufacturing. Having the original engine that came in the car is significant.

Just my opinion.

As for the question about whether it is "worth your time" to keep the M42, well, that's up to you. For many people it isn't, which is understandable considering the cost/benefit, but it's also the reason that cool little cars like the 318is are so hard to find nowadays.

I also agree that 300k km's isn't rebuild territory, at least if the engine has been well maintained. I think you can reasonably expect another 160k km's.
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Old 01-06-2017, 12:31 PM   #9
CanadianDirty30
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300,000km is not really super high mileage. I guess it is for you guys up there but here in texas, that is low miles for the year vehicle you have. my 91 318 had 250k mile on it when I sold it in 08. I bought it with 220k miles on it but I didn't like the m42 engine so that's why I got rid of it.

its like the m20, in how long it will last.
Yea I guess compared to that , it's not high at all haha. But you're correct, here where I live once it gets into the 300k mark people start to not want vehicle at all with that high km

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I wouldn't swap it, at least not without keeping the original engine stored away in the garage.

E30s are not POS disposable econo cars. They are well built, well engineering machines from a high point in German auto manufacturing. Having the original engine that came in the car is significant.

Just my opinion.

As for the question about whether it is "worth your time" to keep the M42, well, that's up to you. For many people it isn't, which is understandable considering the cost/benefit, but it's also the reason that cool little cars like the 318is are so hard to find nowadays.

I also agree that 300k km's isn't rebuild territory, at least if the engine has been well maintained. I think you can reasonably expect another 160k km's.
I agree with you completely, keeping the stock engine would be ideal as most people swap e30s nowadays anyways. That is my main reasoning behind doing the work to repair it. As for the work being put into the I think it might be worth it for that reason, just wanted to hear other people's opinions on the situation first.
But yea I agree it is not in need of a rebuild, I've maintained the engine well. So that will cut some costs there since it won't been everything replaced only certain parts
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