Overheating....head gasket i believe

[Killa B]

im starting to think the 7mge isnt worth a flip. I recently rebuilt the entire engine with all new parts and gaskets, the only parts i left in it are the Piston rods Crank and Cams i had the block head and crank sent to NAPA for machine work and they rebuilt the head for me. Last night i was driving the car and noticed it started to overheat. (I have put about 5K miles on it trouble free) so i had no idea what it could be. I let the engine cool down and started it back up, A LOT of white smoke came out the tail pipe i do not have coolant in my oil or oil in my coolant, however if anyone on here has ever detailed an engine and started it up sometimes you hear like a waterfall noise coming from the engine while sitting inside the car due to water in the cylinders. I was also hearing this noise again (havent detailed my engine) and when i take off the radiator cap and tried to burp the system i have bubbles coming up and it sort of guiser like before the car even starts to warm up. Is it possible that my headgasket blew and im getting coolant into the cylinders? BTW when i rebuilt my engine (im not sure of the spec been looking but cant find it) i know you are supposed to use APR headbolts and torque the head differently than OEM spec. What is this spec? Do i have to use a metal HG because the new one i used was composite i believe?

[cre]

So much to cover here.

The waterfall sound indicates nothing more than air in the heater core....
where the coolant has gone is always the next question though.

If the white smoke smells sweet at all it is most likely coolant. You can absolutely blow a HG and have it do nothing but dump coolant into the cylinders.... The cylinders are surrounded by eccentric elliptical coolant passages (I know you saw them, they're IMPOSSIBLE to miss). Pull your spark plugs and check them for water and look into the cylinders for moisture or to see if any of the piston crowns looks like it's been getting steam cleaned.

The preferred torque is 75ft lbs for bolts... studs use a higher torque; Whether you use ARP or Toyota doesn't matter they're both very solid fasteners and are reusable (although I don't recommend reusing 20+ year old fasteners).

How rough were the engine and head decks? Was everything checked for flatness? Where the head and block inspected for cracks and micro-fractures? Did you put any type of coating on the HG? Did you retorque after a few heat cycles? How many miles have you put on the engine since? Were the threads in the block properly cleaned and chased?

[Killa B]

Originally Posted by cre

So much to cover here.

The waterfall sound indicates nothing more than air in the heater core....
where the coolant has gone is always the next question though.

If the white smoke smells sweet at all it is most likely coolant. You can absolutely blow a HG and have it do nothing but dump coolant into the cylinders.... The cylinders are surrounded by eccentric elliptical coolant passages (I know you saw them, they're IMPOSSIBLE to miss). Pull your spark plugs and check them for water and look into the cylinders for moisture or to see if any of the piston crowns looks like it's been getting steam cleaned.

The preferred torque is 75ft lbs for bolts... studs use a higher torque; Whether you use ARP or Toyota doesn't matter they're both very solid fasteners and are reusable (although I don't recommend reusing 20+ year old fasteners).

How rough were the engine and head decks? Was everything checked for flatness? Where the head and block inspected for cracks and micro-fractures? Did you put any type of coating on the HG? Did you retorque after a few heat cycles? How many miles have you put on the engine since? Were the threads in the block properly cleaned and chased?

i do recall seeing the coolant passages on both sides of the cylinders. The engine and head decks im guessing your talking about the part the HG goes in between, were really smooth after machine work was finished. I dont recall double checking his work on flatness but the master mechanic that helped me rebuild it may have i am for sure checking it if a BHG is confirmed. I was told by NAPA the head and block was checked for cracks and micro fractures. I didnt put any coating on my HG when i rebuilt the engine as i didnt think it would be necessary i was told the metal would heat up and bond the HG to the head and block. I have pt a little over 5K miles on it trouble free other than with the distributor which i think is shot it leaks oil from the weep hole on the bottom side but at a slow rate. Im not sure if the mechanic that did the machine work cleaned and chased the threads in the block but the head bolts were cleaned well with cleaner and a wire brush i do remember putting them in and they went in smoothly. I have been looking into different brand HG's and different materials. I know my previous one was a composite but not sure of the brand i would like to avoid doing more machine work unless it is completely necessary so i want to avoid metal HG's i dont plan on beefing the engine up, so what brand/material HG should i use?

[Killa B]

" The cause for this is inferior quality OEM cylinder head bolts. The factory Toyota bolts do not provide enough clamping force to keep the cylinder head tightly clamped against the block so, over time, the bolts stretch and the head gasket blows out."

I am LITERALLY quoting what jscspeed.com says at the top of the ARP headbolt page

http://www.jscspeed.com/catalog/ARP_...bo-6902-1.html

Is this ACTUALLY true or are they just trying to wean me over into spending more money on ARP Head bolts?
NOTE: My car is a NON TURBO. i do realize this application is only for the 7mgte

[cre]

Originally Posted by Killa B

" The cause for this is inferior quality OEM cylinder head bolts. The factory Toyota bolts do not provide enough clamping force to keep the cylinder head tightly clamped against the block so, over time, the bolts stretch and the head gasket blows out."

I am LITERALLY quoting what jscspeed.com says at the top of the ARP headbolt page

http://www.jscspeed.com/catalog/ARP_...bo-6902-1.html

Is this ACTUALLY true or are they just trying to wean me over into spending more money on ARP Head bolts?
NOTE: My car is a NON TURBO. i do realize this application is only for the 7mgte

That's a complete crock of shit. I've measured 20 year old stockers which had been reused and even over torqued and there was absolutely no sign of pitting or torsional distress. The stock head bolts were installed at 2/3 of their rated, optimum torque (per multiple industrial standards) and generally lasted well over 100K miles... The fact that you see a lot of them fail now isn't surprising in the least... but it's not the fasteners at all. If fasteners don't measure within spec, are pitted or flaking then the must be disregarded but otherwise they are reusable (by design).

Cleaning the thread bores with a wire brush is NOT the same a chasing and chasing must be done for proper torque to be achieved.... It's well known amongst engine builders, general mechanics, machinists and engineers but Toyota was even gracious enough to put it in the TSRM too.

If you had both block and head cut then it's unlikely that the issue is that they weren't flat... at least not flat enough for a composite HG. For one reason or another a coolant jacket AND a bore jacket are not sealing... This is a bit much for a defect to be the culprit. I think that you're most likely dealing with a head that isn't all the way down. There are a couple reasons this could happen; The most common is that the lower, rear timing plate which bolts to the block was not attached to the block when it was machined. These need to be together when machined ad the HG and head lie on top of BOTH. If the timing plate isn't cut the head sits high there, you loose oil out the sides at the very front (how soon this starts happening depends on the offset) and you get coolant passages that are open enough to expel coolant and allow combustion gases in. If the timing plate is cut more than the block you'll find oil leaking into the timing belt area. Also, if you forgot to put the RTV in the specified locations before placing the HG on top of the block you'll get an oil leak out the front sides too.

HG dressing is helpful, especially with older engines.. it's not a must have and with most MHGs it's generally a no-no. I use it on regular paper gaskets and on composite gaskets, The only dressings I use are made by Hylomar but they seem to be getting hard to find around here these days. They are a high heat tolerant adhesive which never solidifies/dries. Permatex copper is what you'll find in a lot of DIY garages though and it's decent enough... just don't use it on anything with a Viton seal. If in doubt look for one that's solvent free.

Composite HGs are decent for even mildly upgraded GTE setups. The head gasket wasn't even the problem with regard to the blowing... not really. MHGs are preferred as they are MUCH more rigid and can tolerate a LOT more abuse... but a thoroughly rebuilt 7M-GTE can take more than a CT-26 can dish out on a stock HG without significant concern provided that everything else has been well planned out too.

ARP bolts are cheap but I really do think of them as interchangeable with Toyota's (Toyota's, not generic). If you feel you need to upgrade your fasteners my only recommendation these days would be going to studs... They're capable of a higher clamping force and you won't find yourself worrying about uneven torque due to a malformed thread in the block creating friction. You just screw the studs in until they're all level and the you torque the nuts down on top.

One other thing to note is that torque specs vary depending on what lubricant was used. I think I posted a table covering a number of fastener sizes and the torque required for various lubricants... can't remember... I might have just found a website with it and posted a link. Anyway, you really only want to use a high molybdenum content grease (aka moly grease).... A dense PTFE (Telfon) grease will work too but I've never tried it for this application so don't consider this a recommendation. The spec of 75ft lbs for head bolts is based on the assumption of well formed (thoroughly chased) threads and a lubricant with a friction coefficient of approx .10 to .12 (such as moly grease). If using a 30wt oil (another common practice but accuracy if reduced) the torque required for the same clamping load goes all the way up to 90ft lbs. ARP sells an assembly lube with a guaranteed friction coefficient... You may use it anywhere on the engine and you'll get far more accurate torque readings. The reason I mention this is that not all lubes are made the same and even the same brand motor oil may have a subtle shift which is really BIG for these types of application.

Had enough? I'm literally falling asleep at the keyboard (no literally, took sleep aids and THEN started this post.... durr.) so I REFUSE to take any blame for any errors or omissions..... I'll fix 'em if I see any tomorrow. G'night and good luck!

[Killa B]

http://www.rockauto.com/catalog/moreinfo.php?pk=122511

Can i still torque this gasket to 75ft-lbs it says grommets and other features protect against over torquing. i just dont know if it talking about over 58ft-lbs or 78ft-lbs

[cre]

It's fine at 75+

[Killa B]

"If you had both block and head cut then it's unlikely that the issue is that they weren't flat... at least not flat enough for a composite HG. For one reason or another a coolant jacket AND a bore jacket are not sealing... This is a bit much for a defect to be the culprit. I think that you're most likely dealing with a head that isn't all the way down. There are a couple reasons this could happen; The most common is that the lower, rear timing plate which bolts to the block was not attached to the block when it was machined. These need to be together when machined ad the HG and head lie on top of BOTH. If the timing plate isn't cut the head sits high there, you loose oil out the sides at the very front (how soon this starts happening depends on the offset) and you get coolant passages that are open enough to expel coolant and allow combustion gases in. If the timing plate is cut more than the block you'll find oil leaking into the timing belt area. Also, if you forgot to put the RTV in the specified locations before placing the HG on top of the block you'll get an oil leak out the front sides too."

where are the specified locations i used ALLDATA to do my rebuild and dont recall it saying anything about RTV i thought you werent supposed to use RTV on a HG? What kind should i use just regular gasket maker?

[cre]

I don't have ALLDATA any more so I'll assume it's incomplete... It's not the first time. No, you don't use RTV as a HG dressing. It may be required to seal unions if specified. In this case it's placed at the union of the rear, lower timing belt housing the block and the HG.

http://www.cygnusx1.net/Supra/Librar...aspx?S=EM&P=55

I don't know why, but there is sufficient pressure there to ensure it will leak sooner or later if the RTV/packing isn't used (ask me how I know).

It's also supposed to be applied here: http://www.cygnusx1.net/Supra/Librar...aspx?S=EM&P=52