Cracked Head/Block?

[Dudeman]

So I was pretty sure I blew a head gasket on the L20B a while back as my 79 620 was burning a ton of coolant. When I got it into the garage I noticed the overflow was completely full while the radiator was low. I tried to add some water but it would just come bubbling out, as if there was excess pressure in the cooling system. I still figured the gasket was toast, so I took off the head and to my surprise the gasket looks totally fine, nothing obviously wrong with it. Could a cracked head or block cause both a coolant leak as well as an excessive amount of pressure in the cooling system?

 

I'm going to have the head pressure tested and if it comes up cracked I'll be on the lookout for anything closed-chamber. If not I'm going to put it back together and hope for the best. Unfortunately I don't have the time, money, or the tools to go through the process of pulling the motor, so if I can't fix it I think I'm going to have to get rid of the truck. :(

 

Any help or advice is always appreciated, and I apologize about the lack of any pics but my digital camera in on the fritz.

[HP11]

I hate to come off lke "Captain Obvious" but did you check the water pump? I only say that because I went through the same thing on a 78 A10 I one owned.

[hang_510]

most blocks have a crack that would cause your symptoms. havent heard about too many cracked heads (i did have 2 small cracks in my U67, not cooling related)

 

my HG failure caused the cooling sysytem to get >50lbs. :eek:

trying running it w/the cap loose and see if it causes any water loss.

[Dudeman]

I haven't yet pulled the water pump (good idea though, I will check that out) but I did run it with the cap off and a funnel in its place, and coolant was bubbling up into the funnel so much that it wouldn't take water even though it was clearly quite low. Hope its not the block, but if that turns out to be the case I'll likely have a super clean 620 for sale.

 

Thanks everyone

[ppeters914]

Cracked block = chuck engine, not the whole vehicle.

[datzenmike]

The new cars have a 'chuck engine' light. :D

 

Was it steaming hot like it was boiling over or just blowing bubbles?

[Dudeman]

When I was driving it home it was definitely running way too hot as the temp gauge was well over 200, but I let it cool down after I made it home. Then I started it up and tried to add more fluid, at which point it bubbled out of the radiator despite a clearly low coolant level, and it was still burning quite a bit of water.

 

Normally I would just pull the motor, but I'm pretty flat broke and school is kicking my ass, so I just don't have the time or money to do it (plus my landlord doesn't want me doing anything more than minor repairs at the house). I may be able to get it towed to the parents place in Marysville and work on it there this summer when I have some money, but I don't think they want me to do that either. I love my truck and if I can find a way to get it fixed up I will, but if the block is cracked there is a good possibility I'll have to get rid of it. Let's hope it doesn't come to that though.

 

Thanks again everyone for the input, it's always appreciated

[DatDoug]

Dude, Dude, Calm down. Your being very un-dude like. If you were closer I would roll over there and help you out. If there is a way you can get it to my house I can fix it for you. If you need a new head or block I can help you there as well. I dont want you to have to sell the truck. Let me know.:D

[datzenmike]

That's right. I replaced my L20B h/g for $23 all by myself. Adjusted out some chain slack so it ran better than before.

[pl521sss]

The new cars have a 'chuck engine' light. :D

 

 

That's funny :lol: :lol:

[ggzilla]

Aluminum heads rarely crack, but sometimes they corrode a hole. A cracked block might do this.

 

Most likely it is your head gasket, you cannot always tell by looking. Better to do a compression test before dissassembling.

 

Another possibility is a problem in the intake manifold of water-heated manifolds, but I don't think the 620 has that type???

[lynchfourtwenty]

yea dude just cause the gasket didnt look blown doesnt mean it wasnt.. i dont think your samurai sword engine block is cracked, if so HOLY SHIT! just have that head checked get a cheap head gasket an change it!!

[Dudeman]

Yeah I talked to the parents and they said it'd be ok to leave the truck at their place for a while, so I don't think I'll have to sell it. I'm not even positive I have a cracked anything, so I'll probably just throw on some fresh gaskets and see where I'm at. If it is cracked tho that'd be a good reason to build a badass L18...:)

[banzai510(hainz)]

http://seattle.craigslist.org/see/cto/1067845146.html

 

probaby a squareport exhaust

[hang_510]

Dude, Dude, Calm down. Your being very un-dude like.

the dude abides :thumbup:

 

HOLY SHIT! just have that head checked

sounds like the right medicine :cough: :mellow:

 

 

 

if needed, tell the landlord that an L-series HG is as minor as it gets :fu:

1/2 day under the hood, provided the TC doesnt drop :D

[datzenmike]

Another possibility is a problem in the intake manifold of water-heated manifolds, but I don't think the 620 has that type???

 

The '78 and '79 had water heated intake (W-58) the '75-'77 didn't (U-67) not sure about earlier ones without looking.

[Dudeman]

So I got the new head gasket on and almost everything reattached, but was having trouble getting the cam sprocket and chain back on. Pretty sure I dropped the tensioner, even though I tried to keep it from falling :mad:

 

Gotta pull the front cover and all, but I'm excited to get her back on the road. Just wanted to say thanks to everyone on the board for providing every piece of information I need to do just about everything I can think of with that L series motor. I'll let you guys know when she's back on the road.