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Replacing Head Gasket: a few questions

18K views 43 replies 17 participants last post by  Spottydog 
#1 · (Edited)
Hi everyone!!!

I'm replacing my cylinder head gasket and doing some other "while you are in there" repairs like the oil filter housing gasket or the water hoses and pipes but I have a few questions that I'm sure you can help me with:

  • What can I use to clean the cylinder block (where the head gasket sits) to remove the old gasket residues?
  • I'm not having problems whit the vanos (no symptoms at all) but my car is 120K miles. The intake piston in the vanos is moving freely, if I push it up it goes down as soon as I release it. Should I replace the vanos seals or leave it alone?
  • What can I use to clean the timing chain tensioners? is it safe to use brake cleaner on them?
  • Is there any other "while you are in there" repair I should do?

I hope to be assembling my car next week end

Thanks in advance!!! Have a great week!!
 
#2 ·
I'm a little concerned that you're doing the head gasket but don't know how to clean off the residue...but I'd start with scraper (carefully), parts cleaner on a rag, maybe a really fine sandpaper if needed, but you need to keep things flat, of course.

Also, did you check that you can apply the needed torque on the head bolts before removing the head.

Since you obviously overheated, that's a pretty common thing guys do to ensure the threads didn't get damaged when it overheated.

Anyway, maybe there's a better method...just don't scrape the head or block.
 
#3 ·
Thank you so much Dmax, it is the first time doing this in a BMW (aluminum block) and the parts cleaner didn't work so well, so I wanted to ask before using sandpaper or scraper...

I didn't check that I can apply the need torque and the head is no longer there, it's in the machine shop to be checked. what should I do if when I get the head I can't get the needed torque?

thanks again
 
#9 ·
If your car overheated to teh point that your headgasket blew, PLEASE PLEASE scrap the motor and buy a new /used motor. When these motors overheat to the point when the head warps or the headgasket blows you CAN NOT simply repair it with a new headgasket and a machined head.

The BLOCK is what gets damaged, its made from a different alloy then the head and it undergoes a chemical reaction when overheated badly and the block will never hold required torque to hold the head down. You can put a BRAND new head and gasket on and do everything and after some time you'll still be overheating as you'll be experiencing head lift due to the block not being able to hold the head down.


If you're replacing the headgasket due to an overheat that blew the gasket I greatly advice you to keep your money and stop repairing the old motor.

The price of a good used motor is 1500-2500 , install yourself within 4-6 hours and be back on the road.

If however you're replacing the headgasket due to a different reason, Id like to hear it
 
#17 ·
It all depends on the situation. I dont know the extend of his damage , it could've been a light overheat that didnt do much damage ....

Isn't there a way he could test the threads before putting the head on? Use a spacer and see if they'll hold?

Also, I wonder if there are rtv appropriate for this application? Maybe a thicker gasket?

Yes yes and yes. When you overheat the motor you MUST check if the block can hold the torque on the bolts before even spending a penny on a rebuild. There is NO specific torque setiing for the head bolts as they are torqued in staged. This means you torque all bolts to 30ft-lb and then do 2 stages of 90 degree turns with a breaker bar

So, undo the headbolts on your overheated motor then follow this
Stage 1:40Nm (30 ft-lb)
Stage 2:+90 degrees (right angle)
Stage 3:+90 degrees (right angle)

If it doesnt hold that then buy a new motor
 
#12 ·
It's all going to depend on if you can get the head bolts to retorque properly or not. If you had a rather lengthy overheat and cooked the block pretty well, your chances aren't great. You can use Timeserts (I think the spelling is correct) to replace the head bolt threads in the block, but there is no guarantee that they won't pull out of the block anyway. You are in a tough spot. I don't envy you that. I would just be prepared for an engine replacement once you get your cylinder head back and can try and torque down some new head bolts.
 
#15 ·
Thanks again to all of you for your help....

Isn't there a way he could test the threads before putting the head on? Use a spacer and see if they'll hold?
I was thinking about this, but I'm worried about causing any damage to the block, so I think I'll wait for the head...


Also, I wonder if there are rtv appropriate for this application? Maybe a thicker gasket?
an appropriate rtv could be a good option, any ideas???
 
#14 ·
There is the oversized head gasket that's available, if that's what you mean. It's for use with decked heads to make up for the machining losses. He could try to torquing on a very thick-walled cylinder of appropriate length. Might work. Otherwise, he is going to have to wait and test with an actual head. (This is only an idea, not a suggestion. I bear no responsibility for the accuracy of such a test. I have no idea if it will work, and meant this as an off-hand comment.)
 
#40 ·
The head seems to be ok, they are only going to clean it, deck it (just .1 mm), check valves, change valve seals and that is it...

I hope this is a good sign.

They are going to charge the equivalent to $250 USD....
Bringing this back from the dead. How did this situation turn out for you?

I'm helping my friend with a 2000 328 with 266k miles replace his head gasket. Even though the coolant temp gauge never saw red, 3 of the head bolts could almost be loosened by hand which makes me worry that the block is finished after reading this thread. We checked for cracks and warpage and the head and block, it has neither.
 
#21 ·
To answer your question, use Chisel Gasket Remover by Loctite. That stuff is very strong and removed about anything. Do not scape the head area with anything.

I am in a similar situation as you. I replaced my head gasket about 7,000 miles ago. Never overheated. Everything was perfect till recently when I noticed the symptoms of the head gasket going again.

I think my mistake was that I scratched up the new gasket a little upon installation and I didn't take 101% of the old gasket material off. Maybe 97% of it. Torque held fine.

Now today, as I'm shopping for the parts to do the head gasket replacement, the needle suddenly goes 3/4 hot and just touches the red zone. I pulled over immediately, joined AAA while I was waiting and called their tow service. Free tow to my home, where she now sits. It starts yo, but runs a little rough.

I am debating if I should redo the gasket properly this time, with the Gasket remover chemical, which I didn't use the last time, just brake cleaner....stupid me.

My thoughts are, I will check if the torque for the head bolts still hold. If it does, I'll redo. If not, I'm on the hunt for a used engine.

I've got 180k miles on it and it ran perfect and very smooth. Had almost everything replaced on it, all new seals, oil separator, vanos seals, etc....So it would be a pitty.

Has anyone had a light overheat like I and had the head still be OK? Is there such a thing as a light overheat?

Thanks
 
#22 ·
I've decided to redo the gasket, have the head checked and time sert all head bolt threads. All this will give me peace of mind. I will be using an engine hoist this time and clean out the surfaces 101%.

With a used engine, I have no idea what it went through and I might start the cycle all over again may be not. I might as well repair mine and I'll know, and it's a lot cheaper.
 
#25 ·
Exactly Alex. If the engine overheated badly, I can imagine even the time serts won't hold and the block itself might be warped. If the over heat was minimal, time serts should be fine. This time I am using the gasket remover chemical and having the head checked again. It should be fine.

Then Time sert. While I am at it I am replacing by Guibo, clutch and rear seal (which is leaking). I am going to use the DIY garage that rents out lifts, hoists and tools in Escondido CA, since I don't have room in my garage for that. AAA gives me 4 100 mile tows, so I am going to use two of them. It's exactly 101 miles, haha.

I'll do all the heavy stuff there at the DIY garage and do all the little stuff at home, like draining fluids, removing intake manifold..and then re-assembling them.

Also bought new motor and transmission mounts. Depending on how the fly wheel looks, I may have it resurfaced. If it looks good, I'll just clean it real good. I have the original flywheel and I only read here that it can't be resurfaced, everyone else says it can. It's only a microscopic layer that would be removed, I don't see the big deal.

Has anyone had good progress on theirs?
 
#29 ·
How did you drill and tap the two back hols by the firewall? Did you use an angle drill? Or did you do it all by hand? I've read people doing it by hand and one guy didn't drill the old thread out at all, just slowly tapped the new thread for the Tim Serts. All worked out.

Curios as to how you did it...and hope everything is OK
 
#31 ·
Did you drill out all the holes by hand, or just the rear ones?

I took my head off and realized it started leaking because 4-5 of the head bolts had stripped their threads or where in the process of doing so. Most were tight.

Make sure you do not over torque the cam caps. The nuts that hold down the cams. They're just 10NM. The cam bolts into the head can slowly strip, if you over torque the nuts (caps) too much when you install the cams. Don't ask me how I know.........
 
#32 ·
I took my head off and found the block already had 30mm time serts. They seem to be fine. I can only conclude the head gasket leaked because I did either did not remove all the old gasket material properly, or I damage the new gasket upon putting the head back on. I had trouble with it and now I know why. The installed time serts in the block make the dowel pins a little wobbly. So I had to wiggle the head a bit before it fell into place. That may have damaged the black gasket material.

It only leaked from cylinder 5. All others were fine. When I put the head back on, I will use a hoist or cherry picker to slowly lower the head without jiggling it. I hope the gasket remover chemicals perform as advertised and as people say.
 
#33 ·
It is finally running again!!!

After working on her yesterday and today its running again!!!

TimeSerts seems to be working good, the temp raised to the middle and I keep her running for about 30 minutes with no problem :thumbsup:

I would like to say thanks to everyone that helped me to fix her.

Special Thanks to jjrichar for this DIY (this should be a Sticky!!!!):

http://forum.e46fanatics.com/showthread.php?t=899347

I used the tools he designed for the timing and every thing went ok!!

I'll keep all of you informed on how this works as the time passes.

THANKS!!!!
 
#38 ·
Special Thanks to jjrichar for this DIY (this should be a Sticky!!!!):

http://forum.e46fanatics.com/showthread.php?t=899347

I used the tools he designed for the timing and every thing went ok!!

I'll keep all of you informed on how this works as the time passes.

THANKS!!!!
hey bro do you have the link to a diy manuel to change the head gasket my intake manifold and exhaust is giving trouble to remove
See the link above......
 
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