Possible cracked head ?

[108Cruz]

In the last couiple of weeks or so I noticed that sometimes my coolant expansion tank is near empty ( almost dry ) and aometimes it's at the full mark.

My dash guage inside the cab always reads just a nick below half and on a hill climb it goes just above half. ( I realize that the guages are not the most accurate ) . The coolant has been changed when I bought the veh. a 1990 LJ71 with the 2LTE motor.

Veh. now has 62000 k's. I only notice a small amount of black smoke on a cold start up and going up steep hills. There is no white smoke at all.

Looking at the expansion tank after a drive you can hear coolant gurgling back into the tank.No leaks noted anywhere, engine bay or on ground.

I read somewhere that if you see bubbles in the expansion tank when you pop the top off that this may be a tell tale sign that you have a cracked head.

Any truth to this. ? My veh. runs great otherwise.

Thanks

Peter

 

[Jan-78FJ40]

In the last couiple of weeks or so I noticed that sometimes my coolant expansion tank is near empty ( almost dry ) and aometimes it's at the full mark.

My dash guage inside the cab always reads just a nick below half and on a hill climb it goes just above half. ( I realize that the guages are not the most accurate ) . The coolant has been changed when I bought the veh. a 1990 LJ71 with the 2LTE motor.

Veh. now has 62000 k's. I only notice a small amount of black smoke on a cold start up and going up steep hills. There is no white smoke at all.

Looking at the expansion tank after a drive you can hear coolant gurgling back into the tank.No leaks noted anywhere, engine bay or on ground.

I read somewhere that if you see bubbles in the expansion tank when you pop the top off that this may be a tell tale sign that you have a cracked head.

Any truth to this. ? My veh. runs great otherwise.

Thanks

Peter

There are some very knowledgeabel people about the 2LT here, so they will hopefully comment.
I don't think you have a cracked head. You would be loosing coolant then, and you did not mention that. The expansion tank is there for exactly that, expansion. If you check the level at varying engine temp, it will be different.

Also, I think bubbles there don't tell you much, you would have bubbles in the filler neck.
let's wait for other opinions, but I would bet your head is fine.
jan

 

[wesintl]

This thread should help you trouble shoot. you can get a combustion tester at napa too for %50

https://forum.ih8mud.com/showthread.php?t=66266&highlight=exhaust+gas+test

 

[light_duty]

Peter,

If you're not losing coolant, you may be okay. It's hard to say. Certainly chucking coolant out the expansion tank was one of the symptoms of my cracked head, but there were differences in my situation as well. If your temp needle stays steady, that's a good sign. Mine would move around quite a bit, and then finally go sky high, with coolant pooling on the ground under the tank. Jan is right - the level in the expansion tank changes a great deal, though it should settle at the around 1/3 mark when the truck is cold.

You may simply have an airlock in the system somewhere. Do a search for "airlock" or "airlocking" and you'll find some stuff on this forum. Do the same search over at www.hiluxsurf.co.uk and you'll find more than you ever wanted to know.

Robin

 

[Gold Boy]

Any bubbles going into the coolant over flow tank when engine is on?

 

[108Cruz]

I went out and let truck idle for about 10 mins. No bubbles noted in expansion tank when engine running ,although it did fill up the tank to about 1/2 in that time.

 

[Gold Boy]

It does not sound as thoe you have cracked head. As your coolant expands when it gets hot it will open the valve on your radiator cap and let some coolant into the expansion tank. And as the coolant cools down the reverse happens.

GB

 

[BJ-44]

Usually if you have a cracked head you will have bubbling in the over flow and it will fill up not lose coolant in the overflow. When the head is cracked it will allow combustion gasses to overpressurize the cooling system, which in turn forces coolant into the overflow. Unless your way low on coolant to begin with.

 

[108Cruz]

posible cracked head ?

Usually if you have a cracked head you will have bubbling in the over flow and it will fill up not lose coolant in the overflow. When the head is cracked it will allow combustion gasses to overpressurize the cooling system, which in turn forces coolant into the overflow. Unless your way low on coolant to begin with.

I do notice the bubbling in the overflow after a drive and I shut off the engine. You can actually hear it without removing the top cap off the overflow tank.

Last night after a drive I checked on the level and it almost filled up the whole tank with 1/2" to spare . I thought it was going to overflow. ( my guages did not go over half temp. ) I took out some coolant to make the level be at half a tank.

I checked back this morning and the tank is almost bone dry.

Do I have a problem if the overflow varies so much. ? Should I just leave the coolant alone and let it overflow as it appears once it cools off the level goes down.

Thanks

Peter

 

[Greg_B]

When cold, and with the pressure cap on, does pressure in the coolant hoses build up with-in a minute, instead of slowly over 5-7 minutes of idling?

gb

 

[light_duty]

Peter, you shouldn't be taking coolant out of the tank while the engine is warm. As you found, if you dump coolant from the tank when it's hot, the tank will empty itself as the engine cools, possibly sucking air into the system. Don't worry too much about how full the tank gets when the truck is hot - that's what it's there for.

It's hard to say for sure, but if you're not losing coolant and you're not overheating, there's likely nothing to worry about. The bubbling may simply be coolant moving through the system. Violent gurgling and visible bubbling IN the expansion tank is probably bad news, because it suggests that coolant is boiling somewhere in the engine. That's what was happening with mine - I would bleed the system but after a few km it would start to airlock (gas in the system), causing localized overheating and boiling of the coolant, followed by a huge puddle on the road. If you're not getting these symptoms, you're probably good.

If I were you, I'd add a mechanical temp gauge. It's cheap and easy to install, and gives you a much better idea of what's happening in the engine. The Toyota gauge blows.

Robin

 

[108Cruz]

Possible cracked head

When cold, and with the pressure cap on, does pressure in the coolant hoses build up with-in a minute, instead of slowly over 5-7 minutes of idling?

gb

Pressure seems to build up over time on a cold start, not right away.

Thanks.

 

[Gold Boy]

If there just a few small bubbles but not "violent" it would suggest to me that you may have an air pocket in your coolant system, and the system is purging its self of any air pocket.

Keep an eye on the over flow and top up when necessary; when the engine has cooled down and is off.

GB

 

[harveya]

It's worth changing out the radiator cap - often the cause of this kind of thing.

Quick test for a cracked head.

Start the engine with the radiator cap off - if coolant bubbles or forces it's way out straight away then you are on to a sure fire head crack - if it takes until the engine starts to warm up then it is a good chance the head is OK.

The 2LT/2LTE engine has a bad history for air locks being difficult to get rid of.

 

[cruiser_guy]

When the head on my '84 BJ60 was cracked I lost probably 3-4 gallons of coolant in 30 miles with clouds of white smoke. I'd suggest if there is no white smoke, chocolate milk looking oil or other signs of a cracked head you're OK.

Park the truck with the nose as high as possible to help with air pockets.

 

[Greg_B]

When the head on my '84 BJ60 was cracked I lost probably 3-4 gallons of coolant in 30 miles with clouds of white smoke. I'd suggest if there is no white smoke, chocolate milk looking oil or other signs of a cracked head you're OK.

And I have seen the situation where there was no white smoke, crystal clear exhaust, no evidence of combustion gases in the coolant with the diesel coolant tester, and no coolant in the oil. The only evidence was a little bubbling in the coolant, and immediate pressurization of the coolant system (within one minute). It was not overheating when driving, and would push the coolant into the overflow. A cracked head was verified when removed.

hth's

gb

 

[cruiser_guy]

And I have seen the situation where there was no white smoke, crystal clear exhaust, no evidence of combustion gases in the coolant with the diesel coolant tester, and no coolant in the oil. The only evidence was a little bubbling in the coolant, and immediate pressurization of the coolant system (within one minute). It was not overheating when driving, and would push the coolant into the overflow. A cracked head was verified when removed.

hth's

gb

Not going to argue 'cause you've seen more trucks than me, but where did the coolant go if it wasn't vapourized (white smoke), in the oil (chocolate looking oil)? I guess it depends on EXACTLY where the head is cracked.

In my case it was at least between EVERY valve in the head, and probably other areas that could not be seen.

 

[Stone]

And I have seen the situation where there was no white smoke, crystal clear exhaust, no evidence of combustion gases in the coolant with the diesel coolant tester, and no coolant in the oil. The only evidence was a little bubbling in the coolant, and immediate pressurization of the coolant system (within one minute). It was not overheating when driving, and would push the coolant into the overflow. A cracked head was verified when removed.

hth's

gb

I witnessed the Cruiser that had this situation that Greg just described...weird, but true.

 

[BJ-44]

Make sure that the radiator is FULL and the cap is good, otherwise if the radiator is low or the cap is bad you will get alot of fluxuation of coolant in the overflow. The just because you have fluid in the overflow doesn't mean you have a full cooling system. Make sure it is cool before removing the cap and filling it. Most of the time the #4 combustion chamber cracks first but slightly and all you will see is bubbling, no smoke and I have never seen water in the oil with a 2LT. Sometimes if the crack is minor I have seen them go weeks in between overheating. It will overheat one day and not the next but there usually was a slight bubbling and it progressively gets worse.

 

[crushers]

i can confirm witnessing 3Bs with cracked heads and no real obvious signs of the cracking till the head was removed.
this account by Greg is completely plausable...
cheers