13b-t head gasket?

[carpet]

so just when i thought everything was going sweet on my first ever engine rebuild project i seem to have run into a problem!!

bit of background first.
over the past 2years i have slowly rebuilt 13b-t in my 74 didn't rush too much well i was only going as quick as spare time and money would let me.
I did all the labour except the machining of the head and bores trying to learn as much as possible keeping in mind i have never done this before.

everything was going well!! well almost everything (i still have a little blue smoke on colder start up) but the truck was driving strong. last long weekend did about 1000km trip (hwy km's) over 3 days with no issue. but took it out this Saturday and had overheating problems, drove fine all day until about 3pm when i noticed steam coming from my overflow(lots of steam) temp gauge in the red. dont think it was there for long as we were just stopped a few minutes prior an i didnt notice anything, and i had been pretty conscious on checking my gauges. let it cool and filled it back up and off we went no dramas for nearly an hour then temp started to rise pulled over and checked coolant and it was low again!!

so my question is do you wise people think it could be the head gasket??? (hopefully not the head!)

got a quick vid illpost up too

 

[gerg]

You can get a carbon monoxide tester from auto parts stores that you to test your coolant to check for combustion gases. Pretty black and white test.
http://www.amazon.com/Lisle-75500-Combustion-Leak-Detector/dp/B0007ZDRUI?tag=ihco-20

id be looking for consistent bubbles in the radiator with the cap off. There shouldn't be any. Did you retorque your head bolts? I'd be checking that too.

 

[carpet]

Hi Greg, nah I didn't re torque the head bolts. Looks like that is the mistake I have made after talking to the engine machinist. I can see some bubbles but not heaps just enough I think to know that it's compression gasses I would think.

He did think that it may be possible to re seal by, undo and re torque each bolt in pattern order cold. Then heat up and repeat the process. He did say to try this before pulling the head off. I might give it a go.

 

[Gengis]

Are the head bolts the new "Stretch" type? If so, did you replace them. Normal bolts look like , well, normal bolts, Toyo stretch bolts have a sort of a spline which you cant use a cheap hex socket on.
I'll post pics if you are not sure.

 

[gerg]

They don't use TTY bolts unless you bought them specifically. I'd go for a good retorque before redoing the head gasket myself as well. Would be crappy to have to redo it, but should just be a clean up and new gasket as long as the heads not warped from the overheat. Not easy to warp a cast iron head, but it is possible. Machining grooves left on the head and block surface can make sealing an mls gasket tuff sometimes. I've used permatex copper sealer with good results. Just a thin layer enough to look wet fills and smooths the grooves. Spray it only on a level surface. Has worked well for me in the past. The gasket already has a nitrile coating so spray the engine and head. More is not better. Be sure to mask everything off. For external use only. Be sure to wear an NCBW suit while spraying. And for heavens sake, to go to the can before putting your suit on.
http://www.amazon.ca/Permatex-80697-Spray-A-Gasket-Hi-Temp-Adhesive/dp/B000HBNUDQ?tag=ihco03-20

 

[carpet]

Hi Gengis, nah they are standard head bolts, not torque to yield bolts i think they are called. Thanks Greg ill keep that in mind if i eventually do have to pull the head. do you have any spec that refers to having to re-torque?? only engine australia where i picked up another gasket from $38 aud (if i need it for the weekend) said that this engine did not require a re-torque. but the machine shop guy said i should. just getting conflicting information.

although now that i have the rocker arms off and checking the torque they are under spec!! im thinking that my engine stand was not rigid enough when i originally mounted the head possibly making it difficult to get the correct torque. or i just stuffed up!! anyway lesson learned so far hopefully this fixes my problem.

will update tomorrow morning.

 

[carpet]

 

[gerg]

So when you put a wheel on and tighten the lugs you check them after a 100km right? Why not check the head bolts. Stuff loosens eventually, never the opposite. Much of the resistance you feel when torquing a head bolt is the thread resistance and not so much the actual clamp of the bolt onto the head. Deburring the threads and using torque lube decreases the thread resistance and give you a more accurate torque which is actually suppose to represent clamp force on the head. We just use bolt torque to extrapolate head clamp force. The more resistance from the bolt threads, the less head clamp you get. After a few heat cycles the bolt will release little areas of resistance on its threads and will feel like It's relaxed and not to spec, the reality is that it might never have been to spec in the first place and you were just measuring bolt resistance and not head clamp. That's why it's so important to have clean threads and torque lube. The loosening effect is called torque scatter. ARP who make amazing studs told me not to retorque. Took me 6 retorques to finally get the studs to hold. That is 6 retorques. One a week for a month and a half. Some of first ones took a full quarter turn. What the heck is up with that? Gets a little tiresome retorquing your head bolts so often, but they finally held tight and never had any further issues. Maybe I had a weird experience, but it has left an impression on me so much so retorquing is just a regular thing after a gasket change. I usually back them off 1/8th and retorque.

 

[carpet]

Yeh I understand! I did clean the bolts and re tapped the tapped holes but I understand what your saying. I just hope the gasket isn't damaged. The new gasket could possibly compress with the first few heat cycles to I guess! Went for a quick drive about half hour didn't notice any excessive pressure build up. Will assess it more tomorrow. Fingers crossed. On a plus though got to give the valve clearance an adjustment.

Thanks for your help

 

[carpet]

Ok a bit of a lesson learned, probably jumped a little quickly to worse case scenario (head gasket), although a re torque of the head bolts was needed!!

After a good drive on Saturday I seemed to have a fully sealed and well functioning cooling system. Let it cool checked the the level under the cap and all was good no air bubbles or leaks. Re fitted the cap and noticed it was not sealing properly!!!!

Squeezing the radiator hose coolant was leaking past the cap and into the overflow! Farrrk I was thinking this was probably the problem all along! Sometimes it would seal sometimes not! I think after 28 odd years the rubber has gone hard under the cap. Anyway new rad cap ordered Toyota had it in stock $16 later all fixed!!

New coolant oil and filter change, one happy boy

 

[Hulsty]

I checked the head bolts on mine about 10,000km after it was built, no change. Have had the radiator cap issue to and some other problems with the thermostat housing.

 

[gerg]

Cool

 

[AJAEbj42]

Good info in this thread!

 

[Hulsty]

I checked the head bolts on mine about 10,000km after it was built, no change. Have had the radiator cap issue to and some other problems with the thermostat housing.

100,000km later I'm getting coolant being pushed out at hwy speeds. Stationary pressure tests (cold and hot) both pass. Investigations to continue.