The cause of the G2 blown Head Gaskets! - Page 3 - The Acura Legend & Acura RL Forum
Acura Legend Forum Acura Legend Forum
 

Auto Insurance

» Featured Product
Wheel & Tire Center

Go Back   The Acura Legend & Acura RL Forum > Acura Legend > Second Generation Legend (1991-1995)

Second Generation Legend (1991-1995)

Acura-Legend.com is the premier Acura Legend Forum on the internet. Registered Users do not see the above ads.
Reply
 
LinkBack Thread Tools Rate Thread Display Modes
Old 09-18-12, 03:46 PM   #31 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
When the back of the intake gets clogged it dose build up heat and dv8 had his egr blocked off for years and didn't do anything. So do come in my thread trying prove me wrong!
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-18-12, 06:05 PM   #32 (permalink)
Registered User
 
klongen1's Avatar
 
Join Date: Oct 2011
Location: Boca Raton Fl
Posts: 55


Car 1: 1991 acura legend 4dr


iTrader Score: 0 reviews
If the egr valve is only slightly clogged with room for air to pass throw still, do I not have to remove my IM?


Sent from my Autoguide iPhone app
klongen1 is offline   Reply With Quote
Old 09-18-12, 06:21 PM   #33 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
Quote:
Originally Posted by klongen1 View Post
If the egr valve is only slightly clogged with room for air to pass throw still, do I not have to remove my IM?


Sent from my Autoguide iPhone app
It depends on how much it's clogged and you will want it done right. So that's a call you have to make. This is just helpful maintenance to keep the cars on the road as long as possible. I'm 8 legends strong and I do this everytime I get 1 and b4 I knew about this and I've only had 1 bhg and that was b4 I knew about this.
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
 
Old 09-18-12, 08:24 PM   #34 (permalink)
sap
Registered User
 
sap's Avatar
 
Join Date: Jul 2008
Location: Edmonton, AB, Canada
Posts: 2,249


Car 1: 92 LS Sedan AT
Car 2: 93 L Coupe 6MT :(
Car 3: 86 Camaro IROC Z


iTrader Score: 6 reviews
Send a message via AIM to sap
Quote:
Originally Posted by CTL View Post
A clogged EGR pipe does not let heat build up. A block off plate absolutely *will* hurt your engine. The actual reason for BHG's is the ECU. When the ECU tells the EGR valve to open, it advances ignition timing to counter-act the effects of introducing inert exhaust gases into the combustion chambers. When the EGR is clogged (or blocked with a block off plate), since there is no exhaust gas in the combustion chambers, but the timing is still advanced, this causes detonation. The headgaskets fail at their weakest point, which is the rear side of cylinders 3 and 6.
All this is on the money, the specific purpose of EGR is to cool combustion to reduce NOx production, which allows for advanced timing without detonation.

The fact that the ECU advances timing when EGR is active is based on sr5guy's disassembly of the ECU software, no more informative and accurate source for us exists.

Advancing timing when it shouldn't be advanced will cause detonation, this is basic and indisputable. The knock sensors can retard timing again once it happens, but it has to happen before they can do that.

A block-off plate has the exact same effect on combustion temperatures that a completely clogged EGR pipe has, and the ECU will advance timing when it shouldn't.

Quote:
Originally Posted by L3GDKANG/JDMKANG View Post
When the back of the intake gets clogged it dose build up heat and dv8 had his egr blocked off for years and didn't do anything. So do come in my thread trying prove me wrong!
I've met you Willie, and I consider you a friend, but you're off-base here. I don't know what chip you've got on your shoulder, but the goal here is to provide the best information, not to prove *anyone* wrong.

There's no explanation, from a heat transfer perspective (which I happen to be quite good at), for a clogged EGR pipe causing "build up heat". The temperature of the cylinder head will be essentially unchanged because the exhaust manifold provides the exit for the vast majority of the gas from the combustion chamber even when EGR is active. The temperature at the back of the intake manifold could be cooler than it otherwise would be (depending on the exact nature of the blockage) because less energy will conduct through the blocked EGR pipe than would normally be transferred by the exhaust gas passing through.

The only reason there would be higher temperatures from a blocked EGR is from the higher combustion temperatures and advanced timing, and this is because a blocked EGR (whether intentionally or not) is not operating properly and the ECU doesn't account for that failure mode.

You can delete, ban, block, edit, do whatever you like to this post or to my account. The simple fact of the matter is that I don't spend much time on either Legend forum anymore and I've got no axe to grind, but would like to see the people who come here for help get the best information available, whether or not anyone has said something to the contrary.
__________________

Visit the Legend Wiki
sap is offline   Reply With Quote
Old 09-18-12, 08:31 PM   #35 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
Lol ok sap. There's a few legends here running egr block offs for years and they haven't had any problems. But they do use a block off plate that's made for it not just to block the holes.
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Old 09-18-12, 08:44 PM   #36 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
This is from sr5's findings
This document will attempt to explain the mystery behind why the Legend’s head gasket blows so frequently and mysteriously and what to do to prevent it. There are various causes to blown head gaskets – it could rot away from neglect (IE: never changing the coolant), it could fail because of severe engine overheating or simply fail from old age. Although I have seen Legends with those problems, the vast majority of failures have been a “mystery” fire ring blowout of cylinder #3. This hypothesis of failure is drawn from my experience doing countless head gasket jobs and 3.5 swaps in conjunction with my full code reverse engineering of the Legend’s engine computer (ECU). I am not an engineer nor do I have a full understanding of the thermodynamics of a cooling system. This document is based on facts that I have collected from years of working on Legends and my recent discoveries of how the EGR system is operated by the ECU.

This is *MY* hypothesis, although it’s not proven - and I’m not sure it COULD be proven - I think I have enough facts to back it up with a fair amount of credibility. To be fair, a fully scientific test would require studying 3 different Legends with factory new engines for a 10 year period of time – something that’s just not feasible. I have done my best to explain relatively complicated concepts in laymen’s terms, if you don’t understand something please inquire and I will do my best to further explain. I am open to debate, but I refuse to argue my hypothesis with someone that is disputing it without hard facts of their own.

Pattern Failure
Just about every Legend I have seen in my shop with a seeping head gasket has failed on the passenger's side rearmost cylinder - #3. The fire ring in the gasket herniates out of the cylinder into the coolant passage on the exhaust side of the head. We will discuss later in this document why the gasket blows like this all the time – pattern failure.

Difficult Diagnosis
What makes them difficult to diagnose is that the head gaskets don’t blow out per se, they “seep”. At the very early stages of failure, the seeping could be intermittent - sometimes even seeming to rectify and re-seal itself. What makes the diagnosis complicated is that the pattern failure of the fire ring acts as a check valve. Small amounts of toxic combustion gasses from the cylinder enter the cooling system on the exhaust stroke, but under vacuum on the intake stroke the fire ring is drawn back into the cylinder preventing coolant from being drawn in and burned. This explains why the stereotypical white smoke from burning coolant isn't present on a Legend with an SHG – making a difficult diagnosis to the uniformed mechanic. I have come across many cars that have had radiators, thermostats and water pumps replaced in the failed diagnosis of a seeping head gasket. Pressure tests, compression tests and block tester kits don’t always give accurate results. The only real way to tell is with a leak down test with a twist – a video of which is stickied in the 2nd generation main section “The Definitive Way to Tell if Your Head Gasket is Seeping”

The Chain Reaction - What Happens with an SHG
When combustion gasses enter the system they displace coolant with air, causing problems with thermostat operation, long term damage to the coolant and corrosion to the aluminum block, head and other metal parts of the system. When the exhaust gasses enter the system under pressure, they displace the coolant, cause the radiator pressure cap to lift and coolant to exit the radiator into the reservoir which usually overflows. This loss of coolant causes large air pockets, and here is where the situation gets really hairy and the car starts to overheat – the thermostat only opens for hot coolant – it won’t open for hot air! At idle the air pocket gets trapped around the thermostat forcing it to say closed. The fan switch is in the lower radiator hose, which is now closed off from seeing the hot coolant from the stuck thermostat (this is why the lower radiator hose is cold), so the fans aren’t running even though the motor is overheating! This causes further pressure in the system and further loss of coolant into the reservoir. When you take off with the car from idle, the increased flow from the water pump pressure causes coolant to flow around the thermostat and it to open again, causing the temperature to drop (this is why the removal of the thermostat will greatly improve the situation and even allow you to drive the car for a time with an SHG). This chain reaction takes place over and over again which is what causes the temperature needle to fluctuate and the heat to come and go. Eventually, all of the coolant is forced out of the system and the engine will severely overheat.

The combustion gasses entering the cooling system are toxic and corrosive. As the gases are passing through the blown gasket, they further corrode and scorch the block and head in that area which allows even more gases to flow into the cooling system. The gases also turn the coolant acidic, causing corrosion to metal and weakening to rubber hoses and seals in the water pump. I have seen the aluminum cylinder liners inside of the motor completely corroded away in severe cases. A bloated, soft upper radiator hose is one of the first bad signs of coolant acidity and is why I recommend replacing all of the hoses when I do a head gasket repair. Other evidence of corrosive gases within the cooling system are dark, gassy smelling deposits underneath the radiator cap and on the overflow hose in the reservoir bottle. There is a very unique smell to the deposits and acidic coolant and I seem to have a nose for it – it sounds weird, but I can almost “smell” a BHG before I even open the hood!

How The Gaskets Blow
Most mechanics will tell you that head gaskets blow because of engine overheating. I don’t believe this is true with the C32. I believe just the opposite – that the gasket blows first which *THEN* causes overheating problems. I believe the gasket blows due to a combination of weak gasket design, the relatively high compression of 9.6:1 and detonation caused by a flawed (and clogged) EGR system and its associated timing maps. This is evidenced by the vast majority of Legends that come in without other cooling system problems - there was nothing that caused the blown gasket - because the gasket blew first! By far, the first symptoms of head gasket problems in a Legend are the forcing of coolant out of the reservoir without any other precursors. I have done many budget head gasket repairs in which only the head gaskets were replaced and EGR cleaned and the car returned to normal operation.

The C32’s pattern failure is herniation of the fire ring in the weakest (lateral) part of the gasket - cylinder #3. If you study any head gasket, you will notice that the holes drilled in it to pass coolant are smaller towards the front cylinders and much larger towards the rear. You will also notice that the holes are larger on the exhaust side of the head than the intake. Since the water pump is at the front of the motor, the varying size of holes drilled in the gasket cause the coolant to circulate evenly to the front and rear cylinders and direct the most coolant towards the “hot spots”. If all of the holes were the same size, coolant would never circulate back to the rearmost cylinders. Since the cylinder is the farthest from the water pump, it has the largest holes drilled into the gasket on the exhaust side. These holes are drilled directly next to the fire ring and there are 3 in total, one round hole in the middle and two larger oblong holes on either side of it. These large holes drilled in such close proximity to one another directly next to the fire ring significantly reduces the gaskets lateral rigidity in this area allowing the fire ring to herniate easily out of the cylinder – the “weak link in the chain”.

This image has been resized. Click this bar to view the full image. The original image is sized 1022x404.

In this photo there are two gaskets laid on top of one another. The top gasket is blown while the lower gasket is a new fel-pro gasket with the fire ring painted green for visibilty. You can see how the steel fire ring has herniated out of the cylinder directly in correlation with the large holes drilled into the gasket. The damaged fire ring is still relatively round except in the area where it is herniated.

This image has been resized. Click this bar to view the full image. The original image is sized 1024x770.


In this photo you can see clearly that the graphite portion of the gasket has been deformed and extruded from the fire ring blowing out of the cylinder. It is clear in this photo that the cause of the gasket failure is excessive cylinder pressures forcing the fire ring out of the cylinder.
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Old 09-18-12, 08:45 PM   #37 (permalink)
sap
Registered User
 
sap's Avatar
 
Join Date: Jul 2008
Location: Edmonton, AB, Canada
Posts: 2,249


Car 1: 92 LS Sedan AT
Car 2: 93 L Coupe 6MT :(
Car 3: 86 Camaro IROC Z


iTrader Score: 6 reviews
Send a message via AIM to sap
Quote:
Originally Posted by L3GDKANG/JDMKANG View Post
Lol ok sap. There's a few legends here running egr block offs for years and they haven't had any problems. But they do use a block off plate that's made for it not just to block the holes.
I suspect it's just a matter of time for them, though obviously I hope that's not the case. Who knows how many years and miles of clogging we endure ...

EGR blockage is EGR blockage, regardless of how it happens.
__________________

Visit the Legend Wiki
sap is offline   Reply With Quote
Old 09-18-12, 08:48 PM   #38 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
I'm just say from what I've seen so far and it has been at least 6 years or more. Now with that said I still run egr's but I tend to do more up keep work on mine then most others do.
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Old 09-18-12, 08:52 PM   #39 (permalink)
sap
Registered User
 
sap's Avatar
 
Join Date: Jul 2008
Location: Edmonton, AB, Canada
Posts: 2,249


Car 1: 92 LS Sedan AT
Car 2: 93 L Coupe 6MT :(
Car 3: 86 Camaro IROC Z


iTrader Score: 6 reviews
Send a message via AIM to sap
Quote:
Originally Posted by L3GDKANG/JDMKANG View Post
This is from sr5's findings
Now that's good information!

... the post directly under the one you copied explains *exactly* what CTL was describing and what I agree with.
__________________

Visit the Legend Wiki

Last edited by sap; 09-18-12 at 08:56 PM. Reason: had the user name wrong
sap is offline   Reply With Quote
Old 09-18-12, 08:52 PM   #40 (permalink)
sap
Registered User
 
sap's Avatar
 
Join Date: Jul 2008
Location: Edmonton, AB, Canada
Posts: 2,249


Car 1: 92 LS Sedan AT
Car 2: 93 L Coupe 6MT :(
Car 3: 86 Camaro IROC Z


iTrader Score: 6 reviews
Send a message via AIM to sap
Quote:
Originally Posted by L3GDKANG/JDMKANG View Post
I'm just say from what I've seen so far and it has been at least 6 years or more. Now with that said I still run egr's but I tend to do more up keep work on mine then most others do.
We would all be lucky if the previous owners of our cars kept up their work
__________________

Visit the Legend Wiki
sap is offline   Reply With Quote
Old 09-18-12, 08:55 PM   #41 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
Yea but even if they didn't it's our turn to do this.
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Old 09-18-12, 10:44 PM   #42 (permalink)
Registered User
 
Join Date: Aug 2010
Location: Atlanta, GA
Posts: 10


Car 1: '91 Acura Legend Cpe (All Stock)


iTrader Score: 0 reviews
The 91 octane is not going to remain controlled detonation under extremely high temps and those temps are achieved when the inert gases from our egr system fail to flow and do their job to lower the combustion chamber temperatures caused by somewhat high compression, advanced timing and fuel metering changes.

It's really that simple. The RL engines can pop when the EGR is ignored too, it's just that most RL drivers are so lethargic in the way they treat the car that it is less common.

just .02 of affirmation on the importance of that clean egr over a block plate hack.

rich
rwheadon is offline   Reply With Quote
Old 10-16-12, 08:38 PM   #43 (permalink)
Registered User
 
Join Date: Oct 2012
Location: southport florida
Posts: 3


iTrader Score: 0 reviews
That makes sense to me. I just bought a 94 legend with all the problems you described. The intake was clogged with 18 years of carbon, no wonder why the computer may be sending the wrong codes. Now I have installed new head gaskets water pump and still cleaning on intake hopefully I'll have it goin soon

Sent from my SPH-M580BST using AutoGuide.Com Free App
stevo94honda3.2 is offline   Reply With Quote
Old 10-16-12, 08:55 PM   #44 (permalink)
Fut RIP
 
L3GDKANG/JDMKANG's Avatar
 
Join Date: Apr 2006
Location: 10-A-KEY
Posts: 10,147


Car 1: 91 Alpha/Alpha Touring KA7
Car 2: 92 Alpha/ AlphaT KA8
Car 3: 91L,93LS,94LS KA7's


iTrader Score: 39 reviews
Quote:
Originally Posted by stevo94honda3.2 View Post
That makes sense to me. I just bought a 94 legend with all the problems you described. The intake was clogged with 18 years of carbon, no wonder why the computer may be sending the wrong codes. Now I have installed new head gaskets water pump and still cleaning on intake hopefully I'll have it goin soon

Sent from my SPH-M580BST using AutoGuide.Com Free App
mak sur you only use oem or felpro head gaskets!
__________________

Yes im back! Alpha/AlphaTouring!https://www.acura-legend.com/vbulleti...ang%2Fjdm-kang
Originally Posted by Blackend
Good to meet you too Willie. I tell ya, when we were walking the Auto-X course and you guys started pulling in, I had no idea who it was until I saw the green machine and we're all like "ooohhhh, that's Willie and the Acuraholicks!"

Glad you guys made it out, and nice meeting all of you.
L3GDKANG/JDMKANG is offline   Reply With Quote
Old 10-16-12, 10:00 PM   #45 (permalink)
Registered User
 
Join Date: Oct 2012
Location: southport florida
Posts: 3


iTrader Score: 0 reviews
What do you think of oil cooler having to do with internal leakage is that a factor that could have caused a blowed head gasket

Sent from my SPH-M580BST using AutoGuide.Com Free App
stevo94honda3.2 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

  The Acura Legend & Acura RL Forum > Acura Legend > Second Generation Legend (1991-1995)


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On


Powered by vBadvanced CMPS v3.2.2

All times are GMT -4. The time now is 02:11 AM.



Powered by vBulletin®. Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
© AutoGuide