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head gasket theory

15K views 30 replies 14 participants last post by  1_Hot_Legend_LS 
#1 ·
so i was talking to a co-worker who is a skilled mechanic and former Jaguar emplyee and we were discussing why most head gaskets blow and his theory was because of the "stretchy" head bolts that acura and most car manufacturers use these days. he was saying that over time these bolts lose their strength and seal, allowing the gasket to leak. u can't re-tighten them when they are on or they will snap. and usually they arent re-useable. (correct me if i'm wrong).

So he was saying, what he has done with all of his cars that he has owned since the 60s is imeadiatly replace the head bolts with performance cold-forged bolts like ones made by ARP:

http://www.arp-bolts.com/pages/products/pages/headstuds/headstuds.html

These bolts are super strong, re-useable and tighten super strong and will not lose their seal. he said that once u install these u will never have to worry about head gaskets blowing.

is this true?

also, i mentioned the copper head gaskets that didn't work and he was saying that in europe they use asbestos in their copper head gaskets and that seals properly, but its hard to use asbestos here because of north american laws.

what are your guys thoughts on these theories? I wish I would have repalced my head bolts before my head gasket blew (would have saved me tons of money!). well, of course u have to keep up on changing the coolant as well...but thats a different story
 
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#3 ·
yah but see your head gasket blew once and then u re-torqed. in order to precent the head gasket from blowing in the first place u would have had to keep re-torqing every how ever many thousand miles. and eventually they will snap after so much torquing.

if u had the strong bolts in the head in the first place, torqed once strong, then you wouldnt have had to replace your HG and then over-torque.

why do u think people have had the HG go twice or more ont hem over time?
 
#4 ·
u dont have to retorque them again and again, its only a one time thing. and u dont want to torque them over 64lbs, have it arnd 60 and you shuld be fine. BTW new head bolts are PRICY :) stick with stock, overtorque (after a HG job) and you should be fine. People whose heads have gone twice or so, have normally not had the job done right the first time. And you will find there are very very few people who have had it go twice on them.
 
#5 ·
It is good practice to replace critical engine fasteners on a rebuild or major repair, and the head bolts would certainly qualify as major fasteners. Overtorquing a bolt or stud can "neck" or stretch it, and it will no longer do the job it was designed to do. Going to 61 instead of 56 or whatever will probably do no harm.

Some mechanics believe it is good practice to re-torque head bolts or studs after the car has been warmed up and cooled down once or twice. Extra work, but perhaps good insurance, as some gaskets do shrink in use, and metal changes shape when heated and cooled.

Having said that, I still think the main causes of HG problems with our cars are:

1. Failure to change coolant regularly (leads to corrosion), and
2. Overheating, due to rad/hose failure, or air in the cooling system.
 
#6 ·
Here's my theory that I discussed with a long time Acura tech. There's a few reasons why the Legend engine blows head gaskets.

Theory #1. The Vibration effect - once you remove the heads, you'll notice that the cyilnder walls sit out in the open by themselves with the coolant jacket surrounding it. No structural support at the top of the cylinder walls. What we discussed was the fact that engines vibrate, and the vibration eventually eats away at the gasket allowing coolant to flow into the cylinder. Typically it does this more at the rear of the engine (#3 and #6 cylinders). Next time you're in your car, rev it up to about 1500-2000 RPM's and feel the vibration that I'm talking about. Think about that vibration happening for 100k-150k miles and how that affects this area of the engine.

Theory #2. Improperly torqued heads - We talked a little about overtorquing heads and he claims that he overtorques the C32a heads to 59-60 lb ft. The theory is that when the engines were built at the factory, the engineers of the C series engines underestimated the torque specs for the heads. The factory torque spec should have probably been 60-62 lb. ft.

Theory #3. Non-Honda coolant - Basically any non-Honda coolant can cause deterioration of the head gasket. See this post for more info: http://www.acura-legend.com/vbulletin/showthread.php?s=&threadid=21171&highlight=honda+coolant
 
#9 ·
misdeismo said:
do u think it would be a good idea to overtorque the heads before a BHG?
No, because not all C32A's have blown head gasket problems. I'm thinking that when the engines were being built in the assembly line, that some fool was using an uncalibrated Torque wrench. Another theory of mine.

I overheated the crap out my 92 sedan one day and to this day the guy that bought it doesn't have any head gasket problems. Making me think that not all the engines have this problem
 
#10 ·
misdeismo said:
do u think it would be a good idea to overtorque the heads before a BHG?
Do you mean to re-torque the head bolts on an engine BEFORE there is any sign of a blown HG??

I think to do this, you'd have to drain all the coolant, then release the bolts, then re-torque them in the proper sequence.

I think I'd stay away from this, as I think it could lead to all sorts of problems.
 
#11 ·
Theory #1. The Vibration effect - once you remove the heads, you'll notice that the cyilnder walls sit out in the open by themselves with the coolant jacket surrounding it. No structural support at the top of the cylinder walls. What we discussed was the fact that engines vibrate, and the vibration eventually eats away at the gasket allowing coolant to flow into the cylinder. Typically it does this more at the rear of the engine (#3 and #6 cylinders). Next time you're in your car, rev it up to about 1500-2000 RPM's and feel the vibration that I'm talking about. Think about that vibration happening for 100k-150k miles and how that affects this area of the engine.
After watching my buddy do the BHG job on the wifes Legend.... I firmly believe this is the #1 reason for the BHG problems on these car..... very wierd design. Those cylinder walls probably vibrate just like a tuning fork and slowly wear away the gasket, and from looking at how the gaskets looked when we removed them.... I really believe that is the cause.

I also agree with some heads not being torqued correctly from the factory.....

The one reason I cannot fully accept in the "Honda" coolant thing..... I have read all the links and stuff..... I am not saying no..... but I find it hard to believe.
 
#13 ·
67GTONUT said:

The one reason I cannot fully accept in the "Honda" coolant thing..... I have read all the links and stuff..... I am not saying no..... but I find it hard to believe.
I really want to do a test, take a set of head gaskets and soak one in Honda coolant, and the other in Prestone, or Zerex. and see which one breaks down the fastest. Maybe do it over 60 days and take pictures of it every 10 days. I know that's probably not the proper way to test it, but I'm sure it would show something.

Vancouver_Legend said:
so no one thinks that my idea of using non-stretch bolts liek the APR ones would help anything?
The bolts need to stretch to gain proper torque. If you used non-stretch bolts, chances are you could rip the threads out of the block. You would also have to figure out a new torque specification because putting 56 or more lb. ft. of torque on non-stretch bolts could squeeze the head gasket too tight, where the stretch bolts give just a little slack. There are pros and cons to it, I would call ARP and ask the pros.
 
#14 ·
Mike Diaz said:
Here's my theory that I discussed with a long time Acura tech. There's a few reasons why the Legend engine blows head gaskets.

Theory #1. The Vibration effect - once you remove the heads, you'll notice that the cyilnder walls sit out in the open by themselves with the coolant jacket surrounding it. No structural support at the top of the cylinder walls. What we discussed was the fact that engines vibrate, and the vibration eventually eats away at the gasket allowing coolant to flow into the cylinder. Typically it does this more at the rear of the engine (#3 and #6 cylinders). Next time you're in your car, rev it up to about 1500-2000 RPM's and feel the vibration that I'm talking about. Think about that vibration happening for 100k-150k miles and how that affects this area of the engine.

s=&threadid=21171&highlight=honda+coolant[/url]
So, the cylinders are free to move at the top of the block (Deck). These are steel barrels, cast into the aluminum block I assume. Perhaps the Honda engineers figured that the heads would "grip" the tops of the cylinders (sort of an interference fit when the heads were torqued).

Interesting. Now what I'm curious about is whether other manufacturers use similar designs, and if so, whether they have problems with head sealing at the cylinders. Any more info on this?
 
#16 ·
Mike Diaz said:
I really want to do a test, take a set of head gaskets and soak one in Honda coolant, and the other in Prestone, or Zerex. and see which one breaks down the fastest. Maybe do it over 60 days and take pictures of it every 10 days. I know that's probably not the proper way to test it, but I'm sure it would show something.
I dunno it sound to me like like they wana make you buy honda brand instead something else. Have they proven this? i mean ud think that if you replaced the gasket (with one made in america) that they would make coolant (also in america) thats bad for it? it just doesnt sound rigth..... anyways in no pro. but it does sound fishy
 
#18 ·
Seeb_95Legend said:
I dunno it sound to me like like they wana make you buy honda brand instead something else. Have they proven this? i mean ud think that if you replaced the gasket (with one made in america) that they would make coolant (also in america) thats bad for it? it just doesnt sound rigth..... anyways in no pro. but it does sound fishy
Until someone does the sort of test that Mike was proposing, we really don't know whether Honda coolant is required, or whether Honda gaskets are better.

My opinion is that until we DO know, it is cheaper to use Honda products than it is to replace a head gasket. There are differences between honda coolant and most of the others. Apparently Honda engineers took a new look at antifreeze in aluminum engines, and decided to produce a different product, rather than add anti corrosion chemicals to existing antifreeze.
 
#19 ·
Tinkindling said:
Until someone does the sort of test that Mike was proposing, we really don't know whether Honda coolant is required, or whether Honda gaskets are better.

My opinion is that until we DO know, it is cheaper to use Honda products than it is to replace a head gasket. There are differences between honda coolant and most of the others. Apparently Honda engineers took a new look at antifreeze in aluminum engines, and decided to produce a different product, rather than add anti corrosion chemicals to existing antifreeze.
If you read this thread: http://www.acura-legend.com/vbulletin/showthread.php?s=&threadid=21171&highlight=honda+coolant

It tells you why Honda coolant is different and non-corrosive like other coolants. I just replaced the radiator in my sedan yesterday. After a year of the coolant being in the system, it looked just like the day I put it in. I am a firm believer that the Honda coolant can do a lot for keeping your head gaskets intact. Other Antifreezes have silicates and borates that can damage the seals on your water pump as well as eat away at the gaskets.
 
#22 ·
I'm still in this thread, now with a new observation. I just did a coolant change on my coupe. 92 LS, 68000 miles, and new rad in March of 2002. That rad was the Acura plastic aluminum job. I actually think this is the best rad, because it does not introduce any more metals into the cooling system, such as copper or brass.

However, I took a really close look at mine, and it is possible that it is starting to seep at the top tank crimp area, right near the rad cap. Since I just changed coolant, I am going to wash it carefully, then dry it thoroughly, and keep a real close eye on it. For what it cost, it ought to last at least 8 or 10 years!

If it is in fact leaking, I'm going to insist that the dealer replace it, and if he refuses, I'm going to push it up to the zone office of Honda Canada. I still have the dated receipt.

But, back on the main topic, I believe that the cost of the rad is peanuts compared to the cost of fixing overheating damage.
 
#23 ·
the thing to do about the plastic topped radiator, is to remove the bracket that holds the throttle and cruise cable from the relay box. Also, you can go around the radiator with a pair of pliers and reclamp the top. That's where mine started leaking at, and I clamped the new one before it does it again.
 
#24 ·
Vancouver_Legend said:
so no one thinks that my idea of using non-stretch bolts liek the APR ones would help anything?
No.. way.. you have no idea... hahahaha
jk...
I have pieced together a hybrid motor, and friends w/ turbo setups..
and i have learned that head bolts are an AWESOME investment in stock or modified application.. yeah they are high but if logevity is your goal.. you need em!..
Like spoon sports.. for their endurance cars.. many of their mods pertain to keeping the motor supported and protected.. from the stress of endurance..:sadwavey:
 
#25 ·
Tinkindling said:
I'm still in this thread, now with a new observation. I just did a coolant change on my coupe. 92 LS, 68000 miles, and new rad in March of 2002. That rad was the Acura plastic aluminum job. I actually think this is the best rad, because it does not introduce any more metals into the cooling system, such as copper or brass.

However, I took a really close look at mine, and it is possible that it is starting to seep at the top tank crimp area, right near the rad cap. Since I just changed coolant, I am going to wash it carefully, then dry it thoroughly, and keep a real close eye on it. For what it cost, it ought to last at least 8 or 10 years!

If it is in fact leaking, I'm going to insist that the dealer replace it, and if he refuses, I'm going to push it up to the zone office of Honda Canada. I still have the dated receipt.

But, back on the main topic, I believe that the cost of the rad is peanuts compared to the cost of fixing overheating damage.
Straight up.. i swear by "koyo" radiatiors" Bang for buck.. their Oem replacemensts are off the chain! :turban:
alli babbah: says: Joo need to buy jourself one.. before i hit you w/ de camel spit!
 
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