Coolant leak - Block heater, head gasket, or cracked block? Help!

[dunk]

86 6.9 truck... Bad coolant leak developed over the past day or two. Noticed a good sized puddle under the truck yesterday, down about 1.5-2 gal of coolant. Puddle was under passenger side mid to rear of engine area. Checked tonight and water pump area looks fairly dry, just some oily residue but does not look like water. From underneath starter area is wet and trans cooler lines show antifreeze dripping off them. Looking above starter it looks wet around the block heater obviously coolant accumulation there. I'm guessing leaking from there but could be from nearby or above.

I was expecting to find an external head gasket leak and was mentally preparing myself for spending Thanksgiving weekend pulling the engine and doing a reseal and freshening up... But rear of head area although a bit wet looks more oily than coolant. No obvious leak, to my weary eyes in the dark at least.

Please have a look at pics and let me know what you think, and also how to tell if my engine is the cracking type or not. I have not used the block heater in the year I've had the truck, not sure if PO used it or how frequently. If my block is the kind the doesn't crack I'd like to replace with a new block heater. Any recommendations or tips on install? Looks like it taps in and secures with a bolt through the middle? After removing the starter it should be reasonable to access.

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[dirtbiker]

Funny, I just had the EXACT same thing happen last week. An 86 motor, transplanted into a 79, was leaving a 12" puddle from under the starter. I also was making plans to do the head Gaskets soon. It was actually coming from the upper radiator hose, at the thermostat housing. Tightened the clamp, and all is dry. It is a longshot, to be sure, but it can't hurt to check. Liquids flow in funny directions.

 

[dunk]

Forgot to mention I did check the upper hose and thermostat housing area. Looks pretty clean and dry. Did tighten the clamps just a hair. ALso there was definite wetness and signs of a leak around the fitting in the head for the heater core. I added a coolant filter a few months back so disturbed all that. Tightened up all those clamps on the 5/8" hose and the one on the head with wetness did tighten up a bit. Didn't look real close at lower as nothing is wet on that side but no gushing leaks.

Trans cooler line was dripping a bit, tightened up clamps on the short rubber from steel line to radiator. Thought that was my sector shaft seal leaking again but that's dry up on the box.

 

[dunk]

Well Advance/Autozone/PapBoys are clueless. Either no idea what a block heater is or think I want glow plugs when I explain it. Guessing they don't carry these. NAPA seems to have them (block heaters) so I'll call them in the AM. What wattage should I get, they list 600 and 1000? They also list 38mm and 41mm... What diameter do our engines take?

From what I've found of pictures these block heaters just seal with an oring around the outside. Guessing that is what failed on mine if it is just the block heater leaking. If I can't get one I may pull it and put a new oring around the outside if everything else looks good. What is the recommended install procedure? Install oring dry? With oil/lube on oring? Or with a sealer like RTV/3bond/whatever slathered around it? Just guessing here based on pictures and without seeing what's actually on my engine. I'm doing an 800 mile round trip Sunday so however this turns out determines if I take the IDI or the 460 truck. I'd rather take the IDI for more range as I'll be able to avoid paying extortionate fuel prices. IDI holds 57 gal 460 holds 38 gal, MPG and fuel cost are roughly the same. And the IDI is a bit more luxurious than my other truck. Must be getting soft...

 

[TahoeTom]

This is what the block heater looks like on the back. The "T" bar only holds it in place and doesn't need to be tightened much. The O-ring is what seals and should be lubed with coolant. You should take some scotchbrite and smooth out the sealing surface. Remove the starter to get better access. I think from mid 85 model year the blocks were reinforced. As you loosen the screw to remove it don't go too far or the T bar will break and fall in your water jacket. The element should be at 11 O'clock.
Edit: Right click on picture and select view image.

 

[quickster]

Call Eastern truck in Linden. They are an I-H shop. They should have it. If your close to Union county.908-862-8856

 

[IDIoit]

i may be incorrect, but that looks like a spot for a freeze plug also.
if you dont plan on using the block heater, install a freeze plug.

 

[dunk]

Well I got a new block heater at NAPA (Kats brand) and tried installing that but it ended up damaging the threads on the center bolt. Maybe I didn't have it set correctly, I had to bend the element a bit to get it to go in and not sit cocked. Didn't take much for that to happen, disappointed. Was gonna run out and get a new center bolt but I liked the other style that was in there, it has a more robust center bolt and thicker flat rear bar vs the thin tapered spreader bar on the Kats.

I put a new oring on the old one and slathered some threebond semi hardening sealer around it. Hopefully it seals and this was the actual leak. The old oring was very hard and brittle. I'll find out soon enough. Wondering if I should have put an oring under the center bolt, couldn't really tell what seals that. Just cleaned it up, looked like maybe a washer under the bolt head.

Starter was a pain to get out of the way, a little tight in there. Unfortunately it doesn't look like I have enough room or a straight enough shot to tap a regular freeze plug in with the engine in the frame.

 

[sassyrel]

i may be incorrect, but that looks like a spot for a freeze plug also.
if you dont plan on using the block heater, install a freeze plug.

any experience with idi freezeplugs????

 

[dunk]

This is leaking again. Ordered a new block heater ZeroStart 310-0043 (http://www.amazon.com/gp/product/B000NM73NW, thanks @fordf250HDXTL) as it looks identical to the old crusty one in there now, whereas the Katz from NAPA was somewhat different and did not fit right. Anyone else have problem keeping these things sealed?

 

[TahoeTom]

I returned a Katz I got from NAPA because it wouldn't fit without bending the element. O'Reillys sells the Zerostart that i used.