The Stovebolt Site Forums The Shop Area Engine Shop Exhaust gas in coolant

A couple of years ago I was having an overheating problem with the 216 of my 1952 1/2 ton. The mechanic said there was exhaust gas in the coolant. I removed the head and sent it to a machine shop. They didn't find any cracks and milled a few thousandths off. I took the radiator to a shop and had it cleaned out. They fixed a couple small leaks. After I reinstalled the head ( with a new head gasket) I back flushed the block. That seemed to fix the problem until a few weeks ago. It doesn't overheat at highway speeds, but when it's idling the temperature gauge starts to move up.
I had the test redone that indicates there is exhaust gas in the coolant again. My question is: is there any point in trying to tighten up the head bolts without replacing the head gasket?

Back up the head bolts about 1/2 turn, and retorque them, one at a time after warming the engine up to operating temperature. It can't hurt, and it just might fix a seep compression leak. Did you use any type of thread lubricant or anti-seize compound when the head was installed? Dry threads tend to under-torque fasteners from thread friction.
Jerry

Hot rod,
No, I didn't put anything on the threads. I will try your suggestion. Thanks for giving me some hope.
Don

Next time, try a dab of Never-Seez on the bolt threads, and just a little under the head. It prevents torque loss from thread friction and gives a better, more uniform stretch to the bolt.
Jerry

I retorqued the head bolts yesterday. So far so good, but the weather only got up to around 70 today. While I was working on it, I discovered one of the spark plugs was loose enough to turn with my fingers- probably unrelated to my overheating problem? Can I wait for a few days and have the coolant rechecked for exhaust gases again?

Does anyone know how long I should wait before I have the coolant retested for exhaust gases?

If you feel the need you can do it right away. That is as long as you have run it long enough to get up to full operating temperature.🛠

What would be wrong with removing each bolt completely in order to apply antiseize?

What about loosening all the bolts at the same time in case the bolts weren't tightened in sequence?

I'm pretty reluctant to loosen all the head bolts at once- - - -too much chance of the head shifting in relation to the block and the gasket and maybe creating areas that won't re-seal. I'd recommend draining the coolant far enough that any open-bottom bolt holes won't create a gusher if the bolts are removed one at a time to apply anti-seize.
Jerry

Dry vs lubed threads is one those highly controversial or contested topics.

In the end it's all about clamping force and that's what the gasket designers were looking for. The clamping force can not be measured in the field and back in the day torque on the fasteners was the best way to get the desired clamping force. Unfortunately the torque variables are very dependent on type of lube and friction and bolt strength and yield. For older vehicles most of the specs were dry torque spec.

Modern car use torque to yield bolts or angular torque, more info below:

http://wbtools.com.au/how-to-understand-angular-torque-and-torque-to-yield/

With certain lubes it is easy to break the bolts before the torque is reached under certain conditions, especially with used or stretched bolts. Several of the articles below will explain and measure the extra clamping force applied and the extra load on the bolts when the threads are lubed vs dry when torqued to the same value.

http://www.engineeringtoolbox.com/torque-lubrication-effects-d_1693.html

http://www.eng-tips.com/viewthread.cfm?qid=173061

http://www.intermotive.net/Tech%20Tip/Tech%20Tip%20-%20Jan%2008.pdf

http://www.automotiveforums.com/t903269-wet_torque_vs_dry_torque.html

http://forums.mtbr.com/tooltime/torque-dry-vs-lubed-716358.html

This one is specific to not using anti seize in their opinion

http://benmlee.com/4runner/threads/threads.htm

I lead off with this post saying it's controversial..............who's going to be the first to break off a head bolt ?

[img]https://volvoforums.com/forum/attac...ken-cylinder-head-bolt-block-step-8a.jpg[/img]

ARP actually has their own thread lubricant, and I can pretty much guarantee that there are no performance engine assemblers that use dry bolts.Even the specs in the manual are for lubricated bolts, using engine oil, but not dry. I have worked industrial maintenance for 40 years, I very rarely install a bolt dry in anything. I would definitely use never seez, if you are really that concerned, the bostick brands actually have a chart of how much to reduce the torque to compensate for this sort of thing.

I reduce the torque spec by 5% when using never seez, and I haven't broken a head bolt or any other lubed fastener in the 40-something years I've been doing it, including building a few hundred race-winning circle track engines. Those folks who disapprove of my methods are cordially invited to observe the sprig of mistletoe attached to my coat tails and act accordingly.
Jerry

Link to ARP .........an excellent tech paper on the topic. They mention the type of surface coating, lube the bolt head surface and reducing dry torque by 20-30% when lube is used. They stress the need for a repeatable method is needed.

http://arp-bolts.com/p/technical.php


I agree lube can be a good.....but.......using the dry torque spec and lubed threads, on used bolts, might cause a novice mechanic some head ache.........this warning or caution Might not apply to the experts in the crowd. ( with or without a sprig)

My engine is still overheating. Not bad but if it sits at idle for a few minutes the temperature gauge starts creeping up ( it didn't used to do that). I was talking to another stovebolt owner about it and he asked me if I had retorqued the head bolts soon after I put the head back on. I had not. In his experience the bolts loosen up within a few hours of running, and this could be the cause of the exhaust gases still getting into the coolant. Does anyone agree with him? He suggested I take the head off again and put a new head gasket on, but this time retorque it after a few hours of driving it. Is that worth a try?