BHG: How bad?

[s.u.p.r.a]

Hey all,

Just pulled the head and found my bhg.

How bad does it look? (minor/severe)

What kind of machining (if any) is probably necessary?

Block: #6 - #4

Block: #3 - #1

Head: #6 - #4

Head: #3 - #1

Thanks for any info.

 

[jdub]

Read this:
http://www.supramania.com/forums/showthread.php?t=59865

It's titled ARP Head Studs, but I talk about replacing the HG.

 

[s.u.p.r.a]

Thanks.

How badly would you rate this bhg 1 - 10? (10 being screwed)

------

Any idea how long this might have taken to get this bad?
I've been driving it for a month since I swapped it in.
If it probably took more than a month I can get a partial refund from the engine company.

 

[starscream5000]

We can't answer that for you, but your machinist can

 

[s.u.p.r.a]

I know you can't tell me very accurately but I'm sure someone can give me a rough guess based on how the HG looks in the pics.

It's not as if I'm gonna throw the head right back on if someone says it doesn't look that bad. :icon_bigg

 

[thelonerider]

Is it just me but I can't seem to see where the HG let go or broke. Is it one of those ugly orange lines? What is all that orange crap, rust? HUH... Were you running straight water in the coolant system? In my case, the break was very obvious between #1 & #2.

BTW, the picture was taken without any cleanup done.
I would not recommend keeping the HG. IMO of course.:icon_bigg

 

[Piratetip]

Cyl 1,2,3,4,5,6 the HG looks like shit & bulging out toward the exhaust side.
Oh and next time don't use so much damn silicon, it looks like you clogged up your coolant passages something terrible.

 

[87targa]

right now it doesn't look really bad but like starstream said, your machinist can. I brought in a 4G63 head that had a bhg, the head looked fine, looked like the BHG wasn't bad. they got it cleaned and...f%#& what the. the head was horrible. my machinist asked me if i found the head sitting on the ground. I was like no it came of a car i'm working on.

not trying to scare you or anything.

 

[thelonerider]

OK, after the above tip, I can see the HG is buldging, but it doesn't look like it was letting any gasses past the seals. BTW, I also wear glasses so I might just be too blind :aigo:
:biglaugh: :biglaugh:

 

[suprabad]

Hard to tell alot from pictures but, you're right about #4 and #6.

On the bright side, you have 2 pistons out of the 6 that are going to be easier to clean....:sarcasm:

Look for cracks between the valve seats and between the combustion chambers, where the metal is thinist. This is usually where you'll find cracks if they are visible.

Get it pressure tested or at least magni-fluxed. Lots of times there will be imperceptible (to the eye) cracks. Also, some times hairline fissures will not show up until the metal gets warm.

Even if you don't see anything suspicious you should still have it checked for cracks, flatness etc., otherwise you're rolling the dice putting it back together. You don't want to have to take it right apart again cause you didn't see the problem.

I've got a dead car sitting in my garage right now (not my supra) 'cause I thought the head looked good. Upon putting it back together I found out otherwise. I know better, but I got lazy and gave in to wishfull thinking. Sometime you get lucky but usually not.

 

[3p141592654]

Did it overheat? That is going to be the main driver behind how much damage there is to the head in terms of warpage, cracks, and annealing damage. Your gasket looks like every other BHG 7M composite gasket with distorted fire rings and collapsed coolant holes. Hopefully the coolant hasn't corroded the aluminum too badly.

PS
Change your coolant more often. Use the red stuff from Toyota too.

 

[rumptis]

I've seen a lot worse....looks like normal 7m BHG to me.

 

[TheRemedy]

whats the best steps in cleaing the head for a BHG...and whats special about the red coolant from toyota?

 

[3p141592654]

The red coolant appears to reduce corrosion significantly. My engine, which has had red coolant all its life had basically pristine water jackets.

In IJ's old build thread he documented significant erosion on his brand new block after only a few months using green coolant. Switching to the red Toyota coolant eliminated the issue.

Leave the head cleaning to the machine shop that will be doing the head resurfacing and valve grind.

 

[TheRemedy]

yes i got my head which they said wasent warped at all really totally rebuilt while it was out of the car...however..what is the best way to prep the engine block and clean it up...someone told me the 3m buffing wheels for a air tool....but im afraid to make it have high and low spots with that..what does everyone suggest..sorry to interupt the thread

 

[bfr1992t]

#1 was leaking. Look at the compression ring around the cylinder and how far it has pushed out to the exhaust side as well as the condition of the rings for the coolant brows, again on the exhaust side. Note some of the gasket has eroded between the two. Also look at the piston top and the combustion chamber (ie the head and valves). Basically, notice how #1 looks significantly different from the rest. The piston top is cleaner than the rest as it's basically being steam cleaned.

The rest of the cylinders look normal, and typical of a well used HG.

Your next steps are to clean the head and block and inspect for gouges, flatness, and erosion. With the condition of your head, I'd just take it to the machine shop and let them clean it unless you have access to a solvent tank.

What's concerning is how much junk there is in the coolant passages. The cooling system needs to be flushed, water pump impeller inspected, and of course, USE A THERMOSTAT when you put it back together.

 

[bfr1992t]

Assuming you do not have a solvent tank or don't plan on rebuilding the head, get the major stuff off with some sort of scraper. I usually use a putty knife. Be careful not to gouge, esp the aluminum head. Keep the blade angle low and flat with the surface you are scraping. Once the major stuff is off, use brake cleaner to help dissolve the more stubborn stuff. The really bad stuff I get with careful use of a razor blade. If you've never done this before, you might start on the exhaust manifold gasket...it will mean much less if you gouge that surface.

Avoid the 3M air tool scouring pads and gasket removers unless you know what you're doing.

 

[ATL88Supra]

on a scale of 1 to 10, thats about a 6.5, i would try and find a new head just in case