BHG block indentations

[AFQC]

Last weekend I suffered the dreaded BHG in my 87 –GE. For the last 3 months I’ve had the mystery of where did the coolant go, usually just a cup or so that was missing from the reservoir. It had the occasional waterfall sound behind the dash but the temps were always stable until last week. On a road trip to Seattle I ran into traffic at Tacoma and came to a stop when I noticed that the temp gauge had risen to about ¾. That was the “oh fuck-BHG” moment. I pulled into the next gas station for a top up. Had to add about half a gallon. Drove it home stopping along the way to top up the coolant. It made it home only having to add maybe a quart. It’s obvious that I had a chamber to coolant passage gasket leak.

Thankfully a good friend let me borrow some wheels while I work on this so time hasn’t been an issue. Thus began the teardown. I’ve been working on it for 2-4 hours a night after work and my mantra with this has been “slow is fast, fast is slow” taking my time to mark everything and keep track of all the bolts and nuts- putting them back in their holes where able. Something I learned from previous work is that old egg crates rule for keeping track of things.

I’ve been of the mindset of replacing everything I can while I’m in it. Timing belt, all coolant hoses, and new OEM head bolts (big props to Mark at Vancouver Toyota for the forums member discount!!) I learned this lesson the hard way on the ’88 that I had several years ago.

Yesterday I got the head pulled off and found that the head gasket was pretty mangled around the #1 cylinder on the exhaust side.

Then I started the process of cleaning off all the old gasket material with a razor when I ran into this.

I was already planning on doing a head resurface with an OEM head gasket but I’m not confident that the indentation in the block on the #1 cyl is going to make a seal.

This is a case for pulling the block and machining the deck right?

 

[Kai]

Stock HG should take up that dink - personally, i wouldn't worry about it. I trust you're going to use ARP head studs instead of bolts?

 

[AFQC]

I've got OEM Toyota head bolts new in the bag but i'm reconsidering ARP now. If I can get a higher torque out of the ARP's it may save headaches later. if I remember right the OEM bolts are really only good for about 75ft/lb until they go plastic whereas the ARP's can go up to 80+ or something like that.

 

[xzeror]

Should use the specs arp gives you, which differ if u use gear oil or the arp moly lube

 

[airhead04]

Arp goes much higher then 80ft lbs

 

[slow_yota]

Sorry to take this OT but I was under the impression that the
waterfall sound was air trapped in the heater core...??
I didnt know it had anything to do with a BHG.

 

[AFQC]

Sorry to take this OT but I was under the impression that the
waterfall sound was air trapped in the heater core...??
I didnt know it had anything to do with a BHG.

It can. When combustion gases get past the head gasket and enter the coolant jackets it will overpressure the radiator cap forcing coolant to overflow into the reservoir. The air bubble in the heater core comes from the combustion gases and air drawn back in from an empty reservoir when the engine cools down.

 

[bioskyline]

that indentation is normal actually for a OEM style head gasket. its casued by the metal ring around the bores in the hg.

with a stock gasket and arps, should be fine for a quite some time, as your non-turbo.

 

[AFQC]

Thanks for the advise guys, I'm going to go ahead with the OEM gasket and hope it holds. Got my head back from the machinist this afternoon and just spent the evening detailing the head and installing the cams. Hopefully I'll have the head back on this weekend.

 

[hvyman]

Arp goes much higher then 80ft lbs

It all depends on the lube used. Dry is something like 60ft lbs. Old arp lube is 80. Ultra arp lube is 90. Oil is 130. Its not the bolt/stud/block/head. Its the lube.

 

[Devin LeBlanc]

Mine was the same way. Im on a felpro gasket from auto zone with bolts and re surfaced head putting 520HP through it. You should have no problems

 

[GrimJack]

Mine was the same way. Im on a felpro gasket from auto zone with bolts and re surfaced head putting 520HP through it. You should have no problems

Agreed. Stock head bolts at 75 foot pounds on a stock gasket should seal that fine for another 20+ years, barring acts of god or bolting a turbo onto it.

 

[AFQC]

Well it looks like I won't be dropping the head today as I had planned. :3d_frown:

I gave it a good 12 hour soak in PB Blaster and it still broke. Any ideas on how to remedy this?

 

[AFQC]

After getting the bolt extracted and waiting for parts, I got the engine together and running today. I haven't done a compression test yet but it seems to be running strong!

 

[Integrity]

Aluminum heads should be milled very slick using PCD (polycrystalline diamond) cutters. Aluminum expands twice as much as iron for the same temperature changes during heat-up and cool-down. A slick surface helps prevent eventual potential abrasion of the head deck against the gasket. Head studs are a little better than head bolts if you have them available. Head bolt torque is critical because the bolts are tightened near the yield point of the bolt material. If you over-tighten, you risk stretching the bolt and forever losing its clamping force. Never re-use a stretched bolt. If you under-tighten due to drag from dirty threads or insufficient lube, you don't get full clamping force. The most accurate torque method is torque-angle. A low torque is used to generally seat the bolt. An angle gauge is then used to control the exact amount of bolt stretch based on the pitch of the threads. Turning the bolt X degrees equals X amount of bolt stretch. Changing bolt lubricant can have a drastic effect on torque sensed by a conventional torque wrench, so be careful if using something unspecified. With regard to milling the block deck, I always do so if depressions exist and one is able to mill it. My shop did over 4,000 engine machining jobs, and I don't recall there ever being a comeback for a repeat BHG following these guidelines. Good luck.

 

[IJ.]

Aluminum heads should be milled very slick using PCD (polycrystalline diamond) cutters. Aluminum expands twice as much as iron for the same temperature changes during heat-up and cool-down. A slick surface helps prevent eventual potential abrasion of the head deck against the gasket. Head studs are a little better than head bolts if you have them available.

Head bolt torque is critical because the bolts are tightened near the yield point of the bolt material. If you over-tighten, you risk stretching the bolt and forever losing its clamping force. Never re-use a stretched bolt. If you under-tighten due to drag from dirty threads or insufficient lube, you don't get full clamping force. The most accurate torque method is torque-angle. A low torque is used to generally seat the bolt.

An angle gauge is then used to control the exact amount of bolt stretch based on the pitch of the threads. Turning the bolt X degrees equals X amount of bolt stretch. Changing bolt lubricant can have a drastic effect on torque sensed by a conventional torque wrench, so be careful if using something unspecified.

With regard to milling the block deck, I always do so if depressions exist and one is able to mill it. My shop did over 4,000 engine machining jobs, and I don't recall there ever being a comeback for a repeat BHG following these guidelines. Good luck.

Interesting post Integ, May I suggest in future could you break it up into paragraphs as no-one will bother reading past the first couple of lines

 

[Master_Spazez]

Mine was the same way. Im on a felpro gasket from auto zone with bolts and re surfaced head putting 520HP through it. You should have no problems

Holy shit that's impressive.

 

[Flateric]

One thing I didn't notice mentioned here is be sure to come back, revisit and give the head a retorque after running for a short time.

Perhaps one of the wiser guys here can offer some type of schedule for this operation. I feel it's important though since as perviously mentioned the alu head and cast block have different thermal expansion/contraction and will cause the gasket to squish out and seat slightly which leads to the torque relaxing ever so slightly.

I can't for the life of me find the article I originally read, but I believe it's after a set number of heat cycles. Or is this only done for metal after market gaskets?

 

[IJ.]

One thing I didn't notice mentioned here is be sure to come back, revisit and give the head a retorque after running for a short time.

Perhaps one of the wiser guys here can offer some type of schedule for this operation. I feel it's important though since as perviously mentioned the alu head and cast block have different thermal expansion/contraction and will cause the gasket to squish out and seat slightly which leads to the torque relaxing ever so slightly.

I can't for the life of me find the article I originally read, but I believe it's after a set number of heat cycles. Or is this only done for metal after market gaskets?

I give my engines 5 full heat cycles with very little to no boost in between then retorque.

 

[AFQC]

I've gone over the recommended 5 heat cycles with burping the coolant and driving to work for 3 days but I will most certainly be doing the retorque after I get back from the Reno Air Races. From what I have gathered the procedure is to break the stiction on each bolt and retorque individually in the assembly pattern right?