BHG - can i drive it to a mechanic??

Mikael_7m

Mikael_7m

Built 7M
Apr 26, 2009
283
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OK so ive definately got a BHG now (huge amount of white smoke and heaps of cappucino), and I want to drive it to a mechanic which is about 30-40 kms away. Is that gonna ruin my motor. I figured ill keep filling the radiator with some water along the way so it doesnt overheat...

Is this a bad idea?? :1zhelp:
 
gaboonviper85

gaboonviper85

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Jan 13, 2008
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This is a horrid idea!!!! I WILL blow your motor and destroy alot of things with it! And unless you don't care if you punch a hole in the side of your block then go ahead and drive it!

Don't drive the car....don't even start it...not even for a second!
 
CyFi6

CyFi6

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Very bad idea with coolant in the oil, although with coolant in the oil a significant amount of damage is already done, you might want to look into a full rebuild so you dont end up with bearing failure soon after you fix the head gasket
 
lewis15498

lewis15498

Don't blame ebay cheapass
Sep 28, 2008
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When you do your rebuild, have the machine shop do a hardess test on the head before machining it. If they dont know what your talking about go elsewhere. When you loose coolant like that, the cylinder head coolant passages fill with steam hot enough to cause annealing. (the metal softens and no longer posseses the integrity to do its job) Its a common thing, you may need a new head. Running the engine will cause this if it hasnt already.
Best of luck.
 
gaboonviper85

gaboonviper85

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lewis15498;1368955 said:
When you do your rebuild, have the machine shop do a hardess test on the head before machining it. If they dont know what your talking about go elsewhere. When you loose coolant like that, the cylinder head coolant passages fill with steam hot enough to cause annealing. (the metal softens and no longer posseses the integrity to do its job) Its a common thing, you may need a new head. Running the engine will cause this if it hasnt already.
Best of luck.
Click to expand...

Not completely true...steam has nothing to do with it...it's the lack of coolant to soak up heat from combustion...no way in hell the steam will get hot enough to anneal the head as aluminum anneals at 720deg F...
 
Mikael_7m

Mikael_7m

Built 7M
Apr 26, 2009
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sorry i should probably clear this up...when i said heaps of cappucino i meant like on the oil cap....ive checked in the sump and the oil is still normal...
sorry for the exaggeration...:3d_frown:
 
gaboonviper85

gaboonviper85

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That doesn't matter....water is getting into your oil either as a vapor or whatever....that hg can let go completely and dump all it's water into the block....then you have big money problems! If your oil is fine now then keep it that way and may get by with just a new hg with proper prep work but if it dumps water in the oil you'll rodknock in two shakes of a jack rabbits ass!

Have the car towed....if there is one thing us here on sm know it's blown headgaskets....it's not something to fuck with!
 
D

Dr Chill

4 hungry Supras
Nov 27, 2007
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^^^ He is right , I bought a 88t with a BHG .... Had water in oil .... Like a dumb shit I just did the HG .... 1 month later my shit was knockin.... Dont drive the supra to the shop ... save yourself the headache later by having her towed .
 
lewis15498

lewis15498

Don't blame ebay cheapass
Sep 28, 2008
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gaboonviper85;1368959 said:
Not completely true...steam has nothing to do with it...it's the lack of coolant to soak up heat from combustion...no way in hell the steam will get hot enough to anneal the head as aluminum anneals at 720deg F...
Click to expand...

Yes, the heat of combustion and the lack of coolant to cool it off is part of it, but I'm pretty sure that the steam boiled out of the coolant plays a role as well. If your low on coolant, you can easily anneal your head without a blown hg. theres coolant in the cylinder head, to cool it somewhat, but not enough and the steam builds in the air pocket and causes the damage.
 
gaboonviper85

gaboonviper85

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Jan 13, 2008
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lewis15498;1368977 said:
Yes, the heat of combustion and the lack of coolant to cool it off is part of it, but I'm pretty sure that the steam boiled out of the coolant plays a role as well. If your low on coolant, you can easily anneal your head without a blown hg. theres coolant in the cylinder head, to cool it somewhat, but not enough and the steam builds in the air pocket and causes the damage.
Click to expand...

yeah sure its possible but its not a completely closed system...the steam will pressurize and find a way out one way or another...it will not be held in one spot long enough to absorb such awesome heat....steam would actually have a cooling effect on the head as more and more steam builds and moves around....either way the head will anneal...but steam isnt the cause......if the steam was completely trapped then sure it could continue to build heat but its not and it will find its way out (threw the bhg and res tank)....think of meth/water injection, the water cools the combustion gasses.
 
Mikael_7m

Mikael_7m

Built 7M
Apr 26, 2009
283
0
16
Australia
Hey everyone ive been reading about rod knock and it occuring after a bhg. :aigo:
Now what are the chances of my 7M getting rod knock. The oil in the sump right now is still normal lookin oil, and i just saw the creamyness on the oil cap when the head gasket blew. Since then i havent driven it at all, except very slowly to get home.
Is there anything I can do, or is it a matter of waiting? Im getting a shop to do the bhg job for me.

Much appreciated for any advice.
Thanks.
 
paradox616

paradox616

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Sep 12, 2008
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Mikael_7m;1368913 said:
OK so ive definately got a BHG now (huge amount of white smoke and heaps of cappucino), and I want to drive it to a mechanic which is about 30-40 kms away. Is that gonna ruin my motor. I figured ill keep filling the radiator with some water along the way so it doesnt overheat...

Is this a bad idea?? :1zhelp:
Click to expand...

coolant is NOT a replacement for motor oil...

"rod knock" occours due to worn bearings (WELL UNDER SIZED) the crank becomes un balanced and the rods begin to do all kinds of crazy things until they snap. when they snap it results in massive engine damage which means you can throw the block away and look for the chunk of cylinder wall.

The proper term for rod knock is spun bearings as the bearing gets soo worn it spins onto the other half and kinda fuses together (happened on my old v6 i pulled down)

you cant inspect bearing condition without pulling the motor apart and pulling a main cap or rod cap off., you can check for a drop in oil pressure but don't use the stock gauge.

previous owner drove my 7m with water in the sump due to a BAD BHG, bearings were destroyed when i rebuilt it 10,000km after, motor had 130,000km on it... bearings last ALOT longer than that in good conditions...
 
gaboonviper85

gaboonviper85

Supramania Contributor
Jan 13, 2008
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paradox616;1372923 said:
coolant is NOT a replacement for motor oil...

"rod knock" occours due to worn bearings (WELL UNDER SIZED) the crank becomes un balanced and the rods begin to do all kinds of crazy things until they snap. when they snap it results in massive engine damage which means you can throw the block away and look for the chunk of cylinder wall.

The proper term for rod knock is spun bearings as the bearing gets soo worn it spins onto the other half and kinda fuses together (happened on my old v6 i pulled down)

you cant inspect bearing condition without pulling the motor apart and pulling a main cap or rod cap off., you can check for a drop in oil pressure but don't use the stock gauge.

previous owner drove my 7m with water in the sump due to a BAD BHG, bearings were destroyed when i rebuilt it 10,000km after, motor had 130,000km on it... bearings last ALOT longer than that in good conditions...
Click to expand...

the crank does not become unbalanced....and no rodknock is not called spun bearings...spun bearings are spun bearings...rod knock is rod knock...although one can lead to the other they are indeed different!

too the op: the milky shit on the oil cap can be from vapor or steam...aslong as your oil itself isnt like milkshake color then you should be good to go! you get rod knock from when coolant mixes with oil..the coolant eats the bearing material!
 
Mikael_7m

Mikael_7m

Built 7M
Apr 26, 2009
283
0
16
Australia
too the op: the milky shit on the oil cap can be from vapor or steam...aslong as your oil itself isnt like milkshake color then you should be good to go! you get rod knock from when coolant mixes with oil..the coolant eats the bearing material!
Click to expand...

This is much better to hear as my oil still looks normal!! I hope! :aigo:
Thanks for clearing that up! :icon_bigg
 
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