[leejoy]

Hi Guys

been gone for a while. Now I'm back with a problem. Appreciate your help please.

I think I blew a head gasket. I'm not sure. I was driving on the street when I opened the throttle and it happened. I saw smoke blowing out the exhaust. I pulled over and saw coolant dripping out from what appeared to be between the cylinder head and the block, and dripping onto the header and causing smoke. There was also smoke coming from the combustion chambers - blowing out the exhaust piping.

I removed the head and took a look. The gasket "appears" to be in very good condition - no visible problems. It's a Felpro PermaTorque. It only has about 1000 miles on it, maybe 2 years old since the rebuild.

I don't know what to do now. Everything looks fine. I can't just throw it back together and hope it's ok. What should I do?

I'm 95% sure it was NOT the intake manifold gasket in case your wondering.

One more thing I want to add. The crankcase had lots of coolant in there. So whatever the problem is, it caused "external" leakage onto the header, and internal leaking into the cylinder(s) and crankcase. This was a "bad" leak. As I said, the gasket appears to be normal. Now I'm thinking the head is cracked.

Lee

 

[oldtimr]

got a pic of the gasket? how bout the head too?

were the bolts tight?

 

[leejoy]

I can send a pic if necessary. I examined it. It appears to be in almost perfect condition. all the bolts were tight. It either blew a gasket or the head cracked. Very frustrating.

 

[Buzzbomb]

Did you make sure that the bolt holes and bolt threads were CLEAN so the torque you put on your head bolts was accurate? Was the block surface and head surface perfectly clean?

 

[leejoy]

yes I did. The head bolts were perfectly clean and torqued in sequence several times, increasing the torque a little bit each time, until torqued to specs. I used RTV on every bolt thread.

 

[M.Maner]

increasing the torque a little bit each time, until torqued to specs.

This may well be the problem. As an example if you tighten a bolt to 20ft.lbs. and then reset your torque wrench to say 25ft.lbs. when you start to pull on the torque wrench you will most likely either see 25ft.lbs on a dial type wrench or hear a click before the fastener ever moves. The same thing happens when you torque a bolt in several steps,the "break away" torque or the torque it takes to actually cause the bolt to turn can be greater than the next step in your torque sequence. I only use two steps when I torque a bolt and the first step is usually no more than 30% of the total and then I go to final torque in the second step. If you can't find anything wrong with the parts used in the engine I would be confident it was the method you used to reach your final torque.
Mike

 

[leejoy]

I read what you said and am thinking about it. Are you saying that I did not "blow" a head gasket, rather, the bolts were not sufficiently tightened and that there were leaks above or below the gasket surfaces? Like I said, the gasket appears to be in perfect condition - no signs of breakage.

What's interesting is this, listen carefully:

I had "external" leakage, dripping on the header
I had "internal" leakage, in one or more cylinders
I had "internal" leakage, in the crankcase (coolant mixed with oil)

so basically, it leaked everywhere. It's as if the gasket is fine, but the bolts were not sufficiently tightened, and maybe the head is not perfectly flat, and high pressure coolant leaked by the head gasket and "squirted" out anywhere it could.

Lee

 

[Buzzbomb]

You said the bolts were cleaned, what about the bolt HOLES? This could also cause the problem M.Maner is talking about , ie. lack of sufficient bolt torque. Did you actually take a thread cleaner and clean the holes out? You can use an old head bolt with a V cut in it for this purpose next time if you didn't do it. The surfaces on head and block also need to be scrupulously cleaned to decrease the risk of failure. Clean them, wipe them with Lacquer thinner, then keep wiping until clean...Then wipe again

I seriously doubt that your head(s) are warped if they are cast iron. It's more than likely a preparation or bolt torque problem..If it was me, I'd chuck the gaskets and get new ones. It's all a matter of how much your time and effort is worth to you.

 

[leejoy]

You said the bolts were cleaned, what about the bolt HOLES? This could also cause the problem M.Maner is talking about , ie. lack of sufficient bolt torque. Did you actually take a thread cleaner and clean the holes out? You can use an old head bolt with a V cut in it for this purpose next time if you didn't do it. The surfaces on head and block also need to be scrupulously cleaned to decrease the risk of failure. Clean them, wipe them with Lacquer thinner, then keep wiping until clean...Then wipe again

I seriously doubt that your head(s) are warped if they are cast iron. It's more than likely a preparation or bolt torque problem..If it was me, I'd chuck the gaskets and get new ones. It's all a matter of how much your time and effort is worth to you.

Dear Buzzbomb and others.

Thanks for your help guys. I cleaned the head bolts, bolt holes (in block) and deck surfaces very well prior to assembly. I even put a drop of oil on the head surface where the bolt head makes contact, to avoid bogus frictional torque, thus allowing true torque readings. Maybe my bolt tightening sequence was faulty. I want to say I used a 3-step torque sequence (following the order shown in my book) method something like this.....

1) 25 ft/lbs (all bolts)
2) 50/ft/lbs (all bolts)
3) final ft/lbs (all bolts) (about 75-85 if I recall)

did I screw up?

Like you, I agree it is unlikely the iron head is warped or cracked. The engine was not even very hot when this happened. I had only been driving it for 5-7 minutes. Just about reaching operating temperature. And it was cool outside, about 75 deg. So it's not like the engine was overheating or anything like that. That makes me lean more towards a head gasket problem and not a cracked block or head. Plus the fact that it leaked onto the header, inside the crankcase, and into the cylinder(s) makes it less likely to be a cracked head or block. If it was a cracked head or block, it would not have leaked into all 3 of those locations.

 

[M.Maner]

Lee,what I suggested earlier about "break away" torque may not be the problem here. When you mentioned using several steps to reach your final torque,I was thinking four or five. The three step process is pretty much the norm. Did you have oil or moly under the head of the bolts? Do you have access to another torque wrench that you could use?
Mike

 

[leejoy]

Lee,what I suggested earlier about "break away" torque may not be the problem here. When you mentioned using several steps to reach your final torque,I was thinking four or five. The three step process is pretty much the norm. Did you have oil or moly under the head of the bolts? Do you have access to another torque wrench that you could use?
Mike

Mike

I used oil under the head bolts. Should I have used Moly? The torque wrench I was using is a "non-ratcheting" Craftsman type. I forget the style name, but it uses a "pointer" on a scale that you simply "watch" as you tighten the bolts. It's not scientific or very accurate. Should I be using a "ratcheting" type torque wrench that is more accurate?

I can't imagine that if a head bolt is over or under torqued by 5-10 ft/lbs that it would make a head gasket fail, but I may be wrong on this. I'm running about 10.5:1 compression and have a .650" lift roller cam with about 260 deg duration if I recall. Typical street performance stuff - not race.

Lee

 

[M.Maner]

Lee,the oil should have been fine and people have used beam type torque wrenchs for decades. Do you recall any of the bolts feeling spongy when you torqued them? Sometimes a bolt will be bad and it may take more travel with the torque wrench to reach the same torque as the others. When that happens the bolt is just stretching(beyond whats normal) and it may be providing very little actual clamping force.
Mike

 

[Buzzbomb]

Mike

I used oil under the head bolts. Should I have used Moly? The torque wrench I was using is a "non-ratcheting" Craftsman type. I forget the style name, but it uses a "pointer" on a scale that you simply "watch" as you tighten the bolts. It's not scientific or very accurate. Should I be using a "ratcheting" type torque wrench that is more accurate?

I can't imagine that if a head bolt is over or under torqued by 5-10 ft/lbs that it would make a head gasket fail, but I may be wrong on this. I'm running about 10.5:1 compression and have a .650" lift roller cam with about 260 deg duration if I recall. Typical street performance stuff - not race.

Lee

Actually, many people believe that the pointer style wrenches are the most accurate wrenches since they really don't need to be recalibrated. The only real problem you can have with them is "parrallax error", which is not really an issue when you are standing right over the wrench looking straight down at the scale. As a matter of fact, many check their click wrenches with a pointer wrench..That being said, it IS easier to use a click wrench.

I've always heard that as long as you creep up on the final value and torque each bolt evenly in the proper order, it doesn't matter if you take more than 3 steps to get there. The key is to hit the final value on the last final turn of the wrench WHILE you are turning the wrench.

You seem to have all the bases covered. I know some people like the no retorque gaskets, but if you did all the steps properly and cleaned everything scrupulously, it's really hard to blame something besides the gasket. I'm not knocking the gasket, as I'm sure many use them with success, but you do have to sort of trust them to be "no retorque" if you are going to use them.

 

[Schurkey]

I used RTV on every bolt thread.

RTV is NOT the right chemical for this application.



Far as I'm concerned, RTV is the most "over-used/used incorrectly" automotive chemical on the planet.

If this were MY engine, I'd be using Loctite 567 or 592 "Pipe Sealer with Teflon" (PST) on those head bolt threads; and Moly lube under the bolt heads.

 

[leejoy]

I don't recall any spongy bolts when I did the install a couple years ago.

I'm having the head checked for problems by a shop. If the shop says the head is good to go, all I can do is reassemble everything with a new head gasket and try it again. I don't know what else to do. I'm not taking the block out of the car to get checked. That's a lot of work and a lot of money. I'll take my chances that it was just a blown head gasket, even though the gasket appears to be fine.

 

[leejoy]

In my opinion there was NOT a leak through the bolts. I understand that the coolant is under pressure (about 10-15 psi) and that leaks through the bolts/threads may occur if not sealed, but if you think about the symptoms I had with the failure, I don't think a single bolt leaking through would have caused my symptoms. I believe only a blown head gasket or severely cracked head is what I've got going on.

That being said, when I do the rebuild, I will use the Loctite thread sealant product you introduced to me. Thanks for bringing that to my attention. With regards to the Moly lube under the bolts heads, I will do that too. Why not. Other people have suggested it as well.

 

[Schurkey]

I believe only a blown head gasket or severely cracked head is what I've got going on.

Or a cracked block deck. THAT would be ugly.

That being said, when I do the rebuild, I will use the Loctite thread sealant product you introduced to me. Thanks for bringing that to my attention. With regards to the Moly lube under the bolts heads, I will do that too. Why not. Other people have suggested it as well.

Don't forget to adjust your torque values downward based on the reduced friction from the PST and the Moly lube.

 

[leejoy]

Or a cracked block deck. THAT would be ugly.


Don't forget to adjust your torque values downward based on the reduced friction from the PST and the Moly lube.

When you say adjust torque values down, that's a red flag to me. I thought the torque values were based on a lubricated bolt head to begin with..........

How do I know if I have a cracked block deck? Can the naked eye see it? I took a look at it and didnt see anything obvious. But remember I had coolant leaking onto the header, into the cylinder(s) and into the crankcase. That would mean the block deck would have to be cracked from the lifter valley side, and across the cylinders to the header side of the block. That's a "BIG" crack. As I recall, it was leaking A LOT from what appeared to be between the block and the head, and dripping onto the ground. I wish I would have examined it more when it was happening, but I was so frightened by the whole event that I shut it down as soon as possible with little time to diagnose and troubleshoot it from fear of catastrophic failure to bearings, etc.

Is there any way to tell just by examining it, or does it have to be magnafluxed or pressure tested?

 

[Schurkey]

When you say adjust torque values down, that's a red flag to me. I thought the torque values were based on a lubricated bolt head to begin with..........

Lubricated with OIL. Moly paste will be more "slippery"; and the PST probably is more slippery (until it sets up), too.

How do I know if I have a cracked block deck? Can the naked eye see it? I took a look at it and didnt see anything obvious. But remember I had coolant leaking onto the header, into the cylinder(s) and into the crankcase. That would mean the block deck would have to be cracked from the lifter valley side, and across the cylinders to the header side of the block. That's a "BIG" crack. As I recall, it was leaking A LOT from what appeared to be between the block and the head, and dripping onto the ground. I wish I would have examined it more when it was happening, but I was so frightened by the whole event that I shut it down as soon as possible with little time to diagnose and troubleshoot it from fear of catastrophic failure to bearings, etc.

Is there any way to tell just by examining it, or does it have to be magnafluxed or pressure tested?

"Real" testing--Magnaflux or pressure--is probably best, but if it was leaking as much as you say, the crack (if there is one) should be very obvious upon careful visual examination.

Might want to assure the deck surface is FLAT and SMOOTH while you have it apart.

Do you have series-flow cooling or parallel-flow cooling? Mark IV or Gen 5/6 block?

 

[leejoy]

Lubricated with OIL. Moly paste will be more "slippery"; and the PST probably is more slippery (until it sets up), too.


"Real" testing--Magnaflux or pressure--is probably best, but if it was leaking as much as you say, the crack (if there is one) should be very obvious upon careful visual examination.

Might want to assure the deck surface is FLAT and SMOOTH while you have it apart.

Do you have series-flow cooling or parallel-flow cooling? Mark IV or Gen 5/6 block?

it's a Mark IV block. I had it at the machine shop 2 years ago for the typical "block prep" machining & testing procedures. They made it perfect. I doubt the block is faulty. I'll look closer for cracks.

The whole head bolt torque thing is a bit surprising to me with regards to the "perfect" torquing procedure. I need an education here. I can't see where if a few head bolts are over or undertorqued by 5 ft/lbs that it's going to cause a head gasket failure. Maybe I'm wrong, but if that were the case, head gaskets would be failing everywhere. It's impossibe to torque every head bolt exactly to specs. There has to be a tolerance of 5-10% or something like that. right?