HG failure vs cracked head--need advise (1 Viewer)

[fishwater]

been tracking down mysterious coolant loss for the past few weeks, that i think i've solved.
let me back up by saying that 3 years ago i replaced my HG and the truck has run great since then. i've had a scanguage for years and watch the water temp on it almost as much as i watch the speedometer and i haven't had any temp much above the mid 190's since i replaced the HG. usually it's right at 188-190 when i'm around town. i noticed the coolant loss in passing, noticing that the overflo bottle was a little low before a trip a few weeks ago. no smoke in the exahust, no rough/slow start ups, idles great w/o a hickup, etc. but the coolant loss worsened and then this week i noticed some foam under the oil cap, and now i have some of the same foam on the radiator cap and a trace amount on the dip stick when it's cold. interestingly, my oil leaks under the truck (pan arch and other leaks have almost stopped).


thanks in advance for any suggestions.

 

[Michael Hanson]

I'd pull it and have the head magna fluxed. Mike

 

[Trapper50cal]

Either way, the head has to come off, so you may as well pull it and see if the head is salvageable or not.

 

[fishwater]

Either way, the head has to come off, so you may as well pull it and see if the head is salvageable or not.

good point. great point. my brain is scrambled. thanks.

 

[fishwater]

if i need one, how long would it take to get a new head? with the truck being my DD, i'm kinda up against the clock.

 

[Trapper50cal]

Well, it will help to do some research on that ahead of time...have one lined up as "known good" and available before taking yours to the head shop. It is what it is unfortunately...gonna be a couple days, I imagine, just to have yours fluxed. If yours does come back clean, you may as well have them do some work while its off...check the valves and valve guides...mill the surface in prep for new gasket, etc.

Rushing it is a sure way to mess it up somehow.

For a head, look in parts for sale and parting out here in Classifieds or Jason at Cruiseryard or Beno or some of the other vendors that deal with 80's here.
If it exists new, CDan will have access to one. And it will be awesome and beautiful and prob. a fair couple pennies.

 

[IdahoDoug]

First, pull the sparkplugs and see if one is different (keep track of which goes to which cylinder). If one is cleaner, you have a HG leak. If you don't see a difference, I think you still have a HG leak. I just erased a bunch of typing telling you how to pressurize the coolant and put dye in it like I did, etc. But no need.

Because you have oil in your coolant, AND coolant in your oil the chances of it being a HG are very high. That's because across the cylinder deck/head junction are many opportunities for the two to mix. Statistically, there are opportunities for this to happen with various head crack scenarios, but way smaller than if it is a HG.

Having said that. If you want to see if you have a cracked head I will retype the bit about the pressure test. Get a flourescent dye kit that includes the glasses and light on a wand. Borrow or rent a cooling system pressurizer. I borrowed one from a mechanic buddy of mine who had the particular adapter the LC needs - a lot of the shop ones dont have this one for some reason. Put dye in the coolant (a lot - who cares, right?) after you've pulled the valve cover so you're looking at the cams. Bring the coolant system to 15psi and turn the lights off and start moving the light around the cams and such paying particular attention to those large Allen plugs and the head bolt holes. If you have a cracked head you will know very fast.

PM me and I'll send you my number and discuss further. This way if it's cracked you've already got some disassembly going on and can order the HG kit and locate a head. If nothing happens, pull the spark plugs and give the engine a crank. If you now see flourescent green splatter coming out a spark plug tube you can celebrate that it's "only" a head gasket.

DougM

 

[fishwater]

First, pull the sparkplugs and see if one is different (keep track of which goes to which cylinder). If one is cleaner, you have a HG leak. If you don't see a difference, I think you still have a HG leak. I just erased a bunch of typing telling you how to pressurize the coolant and put dye in it like I did, etc. But no need.

Because you have oil in your coolant, AND coolant in your oil the chances of it being a HG are very high. That's because across the cylinder deck/head junction are many opportunities for the two to mix. Statistically, there are opportunities for this to happen with various head crack scenarios, but way smaller than if it is a HG.

Having said that. If you want to see if you have a cracked head I will retype the bit about the pressure test. Get a flourescent dye kit that includes the glasses and light on a wand. Borrow or rent a cooling system pressurizer. I borrowed one from a mechanic buddy of mine who had the particular adapter the LC needs - a lot of the shop ones dont have this one for some reason. Put dye in the coolant (a lot - who cares, right?) after you've pulled the valve cover so you're looking at the cams. Bring the coolant system to 15psi and turn the lights off and start moving the light around the cams and such paying particular attention to those large Allen plugs and the head bolt holes. If you have a cracked head you will know very fast.

PM me and I'll send you my number and discuss further. This way if it's cracked you've already got some disassembly going on and can order the HG kit and locate a head. If nothing happens, pull the spark plugs and give the engine a crank. If you now see flourescent green splatter coming out a spark plug tube you can celebrate that it's "only" a head gasket.

DougM

thanks, doug. i've got the dye and i think my buddy has the smaller cap for the radiator pressurizer. need to find a covered area to start the tear down, as i've moved since my first HG job and don't have a garage. hope to line something up tomorrow.
stand by...

 

[landtank]

don't over look the oil cooler as a culprit for allowing coolant to enter the oil system either.

 

[NLXTACY]

I'd pull it and have the head magna fluxed. Mike

Can't do that on aluminum heads. It's gotta be pressure tested.

 

[IdahoDoug]

Well, don't tear down to removing valve covers first - yank the plugs. If one is clean then you're instantly above 90% that it's "only" a head gasket.

I'm glad the oil cooler was brought up. Does that contaminate BOTH coolant and oil? Seemed to me it contaminated the coolant due to the high pressure oil (40+psi) going into coolant. But does the cooler leak normally do both? Looking for input on that.

Anyhow, yank the plugs before anything else to see if it gives you a clue. I'm still voting for HG, but the oil cooler question is valid.

DougM

 

[landtank]

the cooling system maintains pressure long after the engine is shutoff.

 

[fishwater]

here are plugs 1-3 in that order. all look the same to me.
last 3 in next post

 

[fishwater]

4-6 plugs

 

[Trapper50cal]

I'm gonna go out on a limb and say that those plugs all look generally similar and that one doesn't look steam cleaned...

 

[fishwater]

not sure what happened with the pics. some were small and some large, but regardless, the plugs all looked normal/identical to me. none were steam cleaned.

 

[fishwater]

is there any way to diagnose an oil cooler leak vs HG or cracked head?

 

[mickeyt]

http://www.youtube.com/watch?v=oYQHkWVULn8&feature=share&list=PL5E35bvo4WrNXLMWXnERf7zOsQraI7wz9

 

[fishwater]

it seems pretty clear cut, to me at least, that i'm leaking coolant into the oil. i'm just wondering if there's any way to determine if the leak is specifically coming from the oil cooler vs HG/head. one way or the other, i gotta tear something down to find out, i guess.

 

[tomcat]

it seems pretty clear cut, to me at least, that i'm leaking coolant into the oil. i'm just wondering if there's any way to determine if the leak is specifically coming from the oil cooler vs HG/head. one way or the other, i gotta tear something down to find out, i guess.

After 10 years working as a cylinder head repairer i have never seen a head of a !FZ-fe engine crack.. pull out oil cooler and have it pressure tested first, Most head shops can do this for you. if it comes back ok its the HG or block. The OEM head gasket has a small water jacket down near number 6 cylinder that lets go most and the water gets in there. How many miles has the car done ? if you do pull the head have a look at the blocks surface it may need to be decked.( HG will only seal a 2tho difference). when the head gasket comes off remove it slowly , look around all the water jacket holes in the head gasket it self, most gasket leaks are easy to spot.