Blown Head Gasket Symptoms! - Page 6

demon2supra · 05-22-2007, 05:32 AM

well ihave my no 2 cyl at 81 psi on a compression test and the rest range from 155 to 195 on my 88t targa and coolant is rushing thru the over flow and no mixture of oil and water. so head comes of tomorrow, by the way anyone know the weight of the factory flywheel?

carfanatic89 · 05-22-2007, 07:43 PM

Im about to replace my BHG and I was wondering if the block is warped (IDK if that can happen) would I have to take my engine out to get the block machined? How much does it normally cost to get the head machined?

chash360 · 05-22-2007, 11:19 PM

More often the head will warp before the block (I assume it is a 7MGTE or 7MGE with the cast Iron Block and Aluminum Head). Having the head resurfaced is usually a good idea, and not too expensive, especially if it has really over heated when the gasket blew. Resurfacing can also increase your compression slightly, be sure to observe proper torque and tightening sequence, improper head bolt torque causes head warping probably more often than anything else. If you have a turbo and do shave the head for increased compression (not just for the resurface) I highly recommend you get an ARP Head bolt kit to re-install with.

I have never had to resurface the block but there is a first time for everything. Check it with a good flat edge (a good metal carpenters level is usually sufficient), if you can pass a razor blade under it anywhere, it needs work. (a real shaving razor blade not a box cutter blade, if you get a box cutter blade under it its really bad)

I have never done just the head resurface, the last one I did was with a valve job (Pressure Test, Valves and seats polished, new seals and springs, and resurface) for about $460 at a NAPA machine shop.

carfanatic89 · 05-29-2007, 06:57 PM

When I go to clean the gasket material off the block how do I keep it from going into the holes in the block and the piston chamber. I know you can put rags in them but that isnt going to keep all the crap from getting in there. Also if you clean the piston heads (im going to) whats the best sovlent to use or can I just wipe it off (i have never worked on a head or pistons before).

supramacist · 05-29-2007, 08:27 PM

I stuck cotton balls into all of the openings in the block and used a tri-folded towel inside the cylinder sleeves. There's no way to get all of that carbon scouring gone. Time, patience and elbow grease.

chash360 · 05-29-2007, 09:05 PM

If you are going to clean the head without a resurface, careful usage of a putty knife or razor blade scraper can do the job, but it is very easy to scratch the aluminum surface. I have on occasion used copper RTV on aluminim heads to fill minor gouges in the surface, spreading it very thin with a razor blade, just enough to fill the void, (or as a surface release layer when used with porous compound gaskets like felpros, but not on a Supra motor, as I can always find teflon coated metal-graphite laminate gastkets for them.)

The block is much less suseptible to gouging being almost the same hardness as a razor blade or putty knife, but the concerns are the same.
Most any kind of normal solvent can be used if you avoid getting solvent on your valve stem seals or other non-metal parts. Carb cleaner works good for this, even for the pistons, I would shy away from certain types of brake cleaners as they can cause cylinder walls to oxidize and develope a thin layer of rust before you get things back together.

If you resurface the head, you don't really need to do more than a loose cleaning as the machine shop will grind it all off and leave a smooth fresh surface.

You may want to go over your surfaces with a light sand paper or scotch brite, to scuff it up a bit to achieve a better gasket seal (a polished looking surface would almost be too smooth). Be sure none of this sanding debris gets into the cylinders.

I have always used rags in the cylinders to keep out debris, the idea is to remove the rags in a quick motion when finished to pull out any debris that fell in (slightly oily or greasey rags are actually good for this as debris will stick to the rags, and keep the walls from oxidizing.). The same can be done with oil and water jackets using corners of the rags. Use compressed air to get extra debris out of the cylinders, the most critical part. Small bits of debris that may still get in to the oil jackets can be filtered out of the oil through normal operation. Small debris in water jackets can be later flushed out of the cooling system, but rarley causes an issue.

When you re-assemble your enigne, start it up and run it up to normal temp, maybe drive around a little but not hard, then remember to re-torque your head bolts to spec after a couple of heating-cooling cycles. Change your oil and filter within a few days, and flush your cooling system. You are bound to have some bits of debris, and remnants of whatever was happening to the Oil or Cooling system before you fixed it. Don't let this scare you, it sometimes takes 2 complete changes/flushes to get it all out.

supramacist · 06-08-2007, 11:58 PM

Don't be scrrrd. lol

chash360 · 06-11-2007, 07:26 PM

I got really scared the first time I flushed the sytem after my first valve job, and thought oh-no! I missed something big, or that the block was cracked internally somewhere, but after a couple of flushes it was all good.

FYI: citra-safe or equivalent type of citrus solvent works amazingly well on any grease or petroleum based deposits, even hard black carbon deposits and most non-acrylic or non-epoxy adhesives, etc, without attacking seals too bad. Simple Green is a good one too, and being vegatable based they are not a hassle to handle, or danger to your health, enviromentally sound, etc. (they work good as hand and clothes cleaners too)

carfanatic89 · 06-15-2007, 05:59 AM

Thanks for the advice I got the head off and went to the machine shop. I just got it back yesterday, I going to put arp stud in and im having trouble finding them. Ebay which is where i got the gasket set off of doesnt have any listings for a 7mge. All they have it studs for the 7mgte, arent they the same as the 7mge. If not can someone give me a website where I could get them.

chash360 · 06-15-2007, 05:36 PM

The 7mge should be the same set as 7mgte, the t means turbo. The head bolts and manifold studs should be the same. You may end up with 4 extra bolt-nut sets for the turbo, but I don't remember those actually being in the kit. The best gaskets for this motor in my opinion are available from NAPA (its about the only thing I get from NAPA for imports). They are laminated metal-graphite with a teflon coating. Not the 'paper compound' types, even if they have the cylinder and jacket beads (like felpro's), these will eventually disintegrate.

05-22-2007, 11:19 PM	#53
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	Warpage More often the head will warp before the block (I assume it is a 7MGTE or 7MGE with the cast Iron Block and Aluminum Head). Having the head resurfaced is usually a good idea, and not too expensive, especially if it has really over heated when the gasket blew. Resurfacing can also increase your compression slightly, be sure to observe proper torque and tightening sequence, improper head bolt torque causes head warping probably more often than anything else. If you have a turbo and do shave the head for increased compression (not just for the resurface) I highly recommend you get an ARP Head bolt kit to re-install with. I have never had to resurface the block but there is a first time for everything. Check it with a good flat edge (a good metal carpenters level is usually sufficient), if you can pass a razor blade under it anywhere, it needs work. (a real shaving razor blade not a box cutter blade, if you get a box cutter blade under it its really bad) I have never done just the head resurface, the last one I did was with a valve job (Pressure Test, Valves and seats polished, new seals and springs, and resurface) for about $460 at a NAPA machine shop. Last edited by chash360; 05-22-2007 at 11:30 PM.

06-15-2007, 05:36 PM	#60
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	The 7mge should be the same set as 7mgte, the t means turbo. The head bolts and manifold studs should be the same. You may end up with 4 extra bolt-nut sets for the turbo, but I don't remember those actually being in the kit. The best gaskets for this motor in my opinion are available from NAPA (its about the only thing I get from NAPA for imports). They are laminated metal-graphite with a teflon coating. Not the 'paper compound' types, even if they have the cylinder and jacket beads (like felpro's), these will eventually disintegrate. Last edited by chash360; 06-15-2007 at 05:44 PM.

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05-22-2007, 05:32 AM	#51
demon2supra Intake Join Date: May 2007 Location: barnhart,MO Posts: 32	well ihave my no 2 cyl at 81 psi on a compression test and the rest range from 155 to 195 on my 88t targa and coolant is rushing thru the over flow and no mixture of oil and water. so head comes of tomorrow, by the way anyone know the weight of the factory flywheel?

05-22-2007, 07:43 PM	#52
carfanatic89 3" Exhaust Join Date: Apr 2007 Location: Waco Posts: 164	Im about to replace my BHG and I was wondering if the block is warped (IDK if that can happen) would I have to take my engine out to get the block machined? How much does it normally cost to get the head machined?

05-29-2007, 06:57 PM	#54
carfanatic89 3" Exhaust Join Date: Apr 2007 Location: Waco Posts: 164	When I go to clean the gasket material off the block how do I keep it from going into the holes in the block and the piston chamber. I know you can put rags in them but that isnt going to keep all the crap from getting in there. Also if you clean the piston heads (im going to) whats the best sovlent to use or can I just wipe it off (i have never worked on a head or pistons before).

05-29-2007, 08:27 PM	#55
supramacist 1000whp postwhore Join Date: Apr 2007 Location: Escape from the Prison Planet Posts: 1,356	I stuck cotton balls into all of the openings in the block and used a tri-folded towel inside the cylinder sleeves. There's no way to get all of that carbon scouring gone. Time, patience and elbow grease.

05-29-2007, 09:05 PM	#56
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	If you are going to clean the head without a resurface, careful usage of a putty knife or razor blade scraper can do the job, but it is very easy to scratch the aluminum surface. I have on occasion used copper RTV on aluminim heads to fill minor gouges in the surface, spreading it very thin with a razor blade, just enough to fill the void, (or as a surface release layer when used with porous compound gaskets like felpros, but not on a Supra motor, as I can always find teflon coated metal-graphite laminate gastkets for them.) The block is much less suseptible to gouging being almost the same hardness as a razor blade or putty knife, but the concerns are the same. Most any kind of normal solvent can be used if you avoid getting solvent on your valve stem seals or other non-metal parts. Carb cleaner works good for this, even for the pistons, I would shy away from certain types of brake cleaners as they can cause cylinder walls to oxidize and develope a thin layer of rust before you get things back together. If you resurface the head, you don't really need to do more than a loose cleaning as the machine shop will grind it all off and leave a smooth fresh surface. You may want to go over your surfaces with a light sand paper or scotch brite, to scuff it up a bit to achieve a better gasket seal (a polished looking surface would almost be too smooth). Be sure none of this sanding debris gets into the cylinders. I have always used rags in the cylinders to keep out debris, the idea is to remove the rags in a quick motion when finished to pull out any debris that fell in (slightly oily or greasey rags are actually good for this as debris will stick to the rags, and keep the walls from oxidizing.). The same can be done with oil and water jackets using corners of the rags. Use compressed air to get extra debris out of the cylinders, the most critical part. Small bits of debris that may still get in to the oil jackets can be filtered out of the oil through normal operation. Small debris in water jackets can be later flushed out of the cooling system, but rarley causes an issue. When you re-assemble your enigne, start it up and run it up to normal temp, maybe drive around a little but not hard, then remember to re-torque your head bolts to spec after a couple of heating-cooling cycles. Change your oil and filter within a few days, and flush your cooling system. You are bound to have some bits of debris, and remnants of whatever was happening to the Oil or Cooling system before you fixed it. Don't let this scare you, it sometimes takes 2 complete changes/flushes to get it all out.

06-08-2007, 11:58 PM	#57
supramacist 1000whp postwhore Join Date: Apr 2007 Location: Escape from the Prison Planet Posts: 1,356	Don't be scrrrd. lol

06-11-2007, 07:26 PM	#58
chash360 Stock Join Date: Dec 2006 Location: Oregon Posts: 14	I got really scared the first time I flushed the sytem after my first valve job, and thought oh-no! I missed something big, or that the block was cracked internally somewhere, but after a couple of flushes it was all good. FYI: citra-safe or equivalent type of citrus solvent works amazingly well on any grease or petroleum based deposits, even hard black carbon deposits and most non-acrylic or non-epoxy adhesives, etc, without attacking seals too bad. Simple Green is a good one too, and being vegatable based they are not a hassle to handle, or danger to your health, enviromentally sound, etc. (they work good as hand and clothes cleaners too)

06-15-2007, 05:59 AM	#59
carfanatic89 3" Exhaust Join Date: Apr 2007 Location: Waco Posts: 164	Thanks for the advice I got the head off and went to the machine shop. I just got it back yesterday, I going to put arp stud in and im having trouble finding them. Ebay which is where i got the gasket set off of doesnt have any listings for a 7mge. All they have it studs for the 7mgte, arent they the same as the 7mge. If not can someone give me a website where I could get them.