Removed Head...anyone else found a loose head bolt? (1 Viewer)

[flintknapper]

Removing head today (pursuant to this thread)

Maintenance...Water Pump, T-Stat, Oil Cooler, Flush Engine/Radiator, now head-gasket blown :(


All except for one were tight as should be. A single bolt (exhaust cam side #6) was very loose. I would guess no more than 30-35 ft/ lb.

I did a quick search and didn't turn up anything. Has anyone else experienced anything like this?

Original head gasket, head has never been off before. 316K miles on engine.

Thank you in advance.

Edit: I did not find anything visually apparent with my head gasket but clearly it was leaking there.

Wondering also if I should expect to find warpage of the head in that spot?

 

[jpoole]

Did you check the thickness of that bolt against the others? These torque to yield bolts sometimes show failure/wear through a reduced diameter as I understand it. I've only seen this contraction in acute cases where it's visually obvious but the FSM does provide specs to measure the head bolts against so this could help you ascertain if the bolt failed vs. possibly being insufficiently torqued which I assume are two of the most likely explanations here.

You could also setup a test torque situation where you tried to run this up to factory torque to see if it could handle that or if it stretched/failed first which could also indicate it's a failed/compromised bolt.

 

[flintknapper]

Did you check the thickness of that bolt against the others? These torque to yield bolts sometimes show failure/wear through a reduced diameter as I understand it. I've only seen this contraction in acute cases where it's visually obvious but the FSM does provide specs to measure the head bolts against so this could help you ascertain if the bolt failed vs. possibly being insufficiently torqued which I assume are two of the most likely explanations here.

You could also setup a test torque situation where you tried to run this up to factory torque to see if it could handle that or if it stretched/failed first which could also indicate it's a failed/compromised bolt.

That particular bolt was 'gritty' feeling nearly the entire way out and had a small amount of light rust on it. It had a spot in the threads that was visually narrower than the rest. It measured under the minimum for reuse but was not the only the bolt to measure under size. I have new head bolts anyway and do not plan to reuse any of the old ones.

I am bit concerned about head warpage since that bolt was right in the corner of the head. I would be less concerned had it been in the middle. There was coolant present at this cylinder only. I'll have a better look at it today.

I wasn't planning on having the head reconditioned at this point as I am going to pull the entire engine this fall when I have more time and can go through it then . I was really wanting to just get it back up and running for now.

So I'm thinking about stripping the head down, taking it in to a machine shop (we don't have many here) and have them check it for straightness, then Vat it and surface it if needed.

I was just very surprised to find a loose head bolt (lesser torque than normal). The others were darn sure tight, you'd swear they are going to break with all the 'cracking' sound they make at first.

 

[Rusty Marlin]

Do you have a steel rule, a good one, like a 10" or 12" Starret?

 

[flintknapper]

Do you have a steel rule, a good one, like a 10" or 12" Starret?
View attachment 2299447

No, but.....got a precision straight edge on the way.

 

[mehbohdi]

You can't check a head with a 12 inch steel rule, you need a machinist straight edge, it needs to be at least, as long as head so you can check corner to corner.
You can't get a reliable measurement from a steel ruler 12 inches long.

 

[BILT4ME]

You can't check a head with a 12 inch steel rule, you need a machinist straight edge, it needs to be at least, as long as head so you can check corner to corner.
You can't get a reliable measurement from a steel ruler 12 inches long.

And for how much those cost, take it to the machine shop and have them check and mill it, and rebuild it.

 

[jpoole]

It had a spot in the threads that was visually narrower than the rest.

Sounds like the bolt failed at that point and I assume that the narrowed section was outside of the block, even though it was threaded. Does make you wonder when/how the bolt failed. Sounds like the threads in the block need to be cleaned up.

At this point having the head inspected and cleaned up by a shop seems like a good idea. You shouldn't have to redo the head work in the fall even if you pull it back off the block at that time, unless I'm missing something. I would assume pretty fast turn around time on the head service unless your shop availability is too limited. Where I am I paid $350 and the head was only with the shop a few days. They did a valve job including installing seals that I provided, set lash, surfaced, pressure checked and thoroughly cleaned the head.

 

[Kernal]

Interesting. While watching the OTRAMM head gasket video when he went around for a fourth pass to make sure all the (ARP) head studs were still at 80ft lbs, the last bolt, exhaust side #6, had loosened up. None of the others were loose. The head had been milled before reinstalling.

 

[Kernal]

Interesting. While watching the OTRAMM head gasket video when he went around for a fourth pass to make sure all the (ARP) head studs were still at 80ft lbs, the last bolt, exhaust side #6, had loosened up. None of the others were loose. The head had been milled before reinstalling.

 

[flintknapper]

You can't check a head with a 12 inch steel rule, you need a machinist straight edge, it needs to be at least, as long as head so you can check corner to corner.
You can't get a reliable measurement from a steel ruler 12 inches long.

I've got a 24" Starrett coming.

 

[flintknapper]

Interesting. While watching the OTRAMM head gasket video when he went around for a fourth pass to make sure all the (ARP) head studs were still at 80ft lbs, the last bolt, exhaust side #6, had loosened up. None of the others were loose. The head had been milled before reinstalling.

Good observation, I remember seeing that too....but it didn't really mean anything to me until now.

 

[jpoole]

I've got to assume that what OTRAMM experienced and what happened with your head are different in that he didn't appear to have stud failure as he could complete full torque on that final pass. You did apparently have bolt failure as evidenced by the narrowed area on the bolt that you reported. If your bolt was loose due to incomplete torque I don't think it could have ever then stretched to failure.

I'd say your bolt either failed during install torque or later when heat expansion stretched it to the point of failure.

 

[flintknapper]

Sounds like the bolt failed at that point and I assume that the narrowed section was outside of the block, even though it was threaded. Does make you wonder when/how the bolt failed. Sounds like the threads in the block need to be cleaned up.

^^^^^

I will be sure to clean up all the threads. I have the proper tap for it (odd size: M11 x 1.25)

 

[IdahoDoug]

Yes, chase the threads for sure. To clean them first, you can use a thin vacuum line duct taped into a crevice tool on your shop vac. Fire some PB down there brush with a tiny tubular brush (WalMart) and let it sit, suck that out. Repeat with brake cleaner, etc. When I clean the head bolts on a project engine in the stand, I flip it and fire cleaner UP into the holes and blast it out and let gravity flow it out. Follow ARP's dry bolt/lubed bolt for torquing it, not Toyota's.

 

[landtank]

I know that if you do a second pass during the initial head bolt torquing (29ftlbs ?) you will find the center bolts are loose. I've thought it was do to the head gasket compressing some during the process.

 

[fz1boxer]

I know that if you do a second pass during the initial head bolt torquing (29ftlbs ?) you will find the center bolts are loose. I've thought it was do to the head gasket compressing some during the process.

That is correct,we used to heat cycle a couple times after final torque then recheck torque readings.

 

[landtank]

That is correct,we used to heat cycle a couple times after final torque then recheck torque readings.

these heads get an initial torquing of 29ftlbs (if memory is right) and then two more 1/4 turns (if memory is right). They are torque to yield. So it was the inital 29ftlb torque that I was referring to and doing it a second time as the bolts at the center would be light.

 

[maxamillion2345]

I really think you may as well take the head in, surface, crack test, have them check valves/seats, replace all the stem seals, and adjust valves. I paid IIRC less than 400$ to have all that done on my 1FZ head. Then if you tear the head off down the road, just hit it with a roloc and its good to go.

 

[flintknapper]

At this point having the head inspected and cleaned up by a shop seems like a good idea. You shouldn't have to redo the head work in the fall even if you pull it back off the block at that time, unless I'm missing something.

^^^^

It might come to this...but IF I can get away cleaning it up, lightly lapping the valves and installing new valve stem seals, then that's what I would prefer because when I go through the engine later, I want everything to be fresh.

I started cleaning up the head today in order to do a preliminary inspection (I.E. check for warpage, look at valve seats and guides, check spring height) . I can check all of that myself. Then IF I see any trouble spots, I'll send it off to a machine shop.

Not many around here...so I may have to drive an hour or so to find a trustworthy shop. Obviously... I can't pressure check it or do a good job inspecting for cracks. And then too....a good shop can 'VAT' it and get it really clean. But I still want to look at myself first. (I know...it sounds like a 'control freak' kind of thing)...but when you live around only small towns...you can't trust just anyone to do this. If it was a '97 Chevy Pickup....yes, but it's not.