Brinell Test

[smmgf51]

Hi

Any advice on Brinell test on a K-Series cylinder head to eliminate any doubts before re-using? mgf 2001

I am wondering if the Brinell test should be done around the area where the liners meet and whether peening the head in this area will then change the result.
Or will a Brinell test leave too deep an imprint on an otherwise okay head?

Thanks

[Mykel]

If I had the tool to do it (seriously pondering buying one off Aliexpress), I would probably measure somewhere inbetween the fire rings, where the mating surface with the gasket would not be affected in critical areas, or even inside the combustion chamber, valves permitting due to tool size.

We have been asking a lot of engine “specialists” over here, and none of them even knows what a brinell test is. They usually just skim, do a pressure test to see if the valves are tight and that’s about it.

[Reckless Rat]

For the uninitiated a Brinell test is used to determine the hardness of a metal object. The tool has a ball bearing at the end which is placed on the metal to be measured and then the tool is given a predetermined pressure. A second tool, a bit like a small telescope is then used to measure the diameter of the indentation and the degree of hardness can then be compared to the Brinnell scale. The bigger the indentation the softer the metal.

For the geeky types, here's some more info: https://www.hardnesstesters.com/test-ty ... ss-testing

Diamond point hardness testing is another option and is less invasive than the Brinell method.

Looking at the head in Mykel's photo I would suggest that it's "Castleton" (beyond Hope) due to the indentations around the fire rings.

When I was involved in non-destructive testing in a former life (a long long time ago) in a Sheffield steelworks, we had a portable Brinell tester which was basically a hardened steel ball machined on the end of a cold chisel shaft, which was given a sound whack with a lump hammer. It was somewhat arbitrary, but there is a limit on how hard you can hit something with a lump hammer so the force applied was roughly constant. However this was being used on very large ( up to 140 tonnes) steel castings & forgings which were a lot harder than an alloy head. We used diamond point testing on machined stock that had been heat treated to determine the depth of case hardening.

[mgtfnut]

Has anyone experience of this service? I've looked at it over the years and wondered if it practical and effective. Not seen much about it. Worth a contact?

http://www.modusengineservices.co.uk/ro ... ution.html

[smmgf51]

So what experience has anyone got with the various hardness testing options?
I had taken a quick look around at the options but not yet selected somewhere to get a test done.
So for Brinell or Diamond point testing is there a list of what's a good or bad result when its tested? I think I have seen this for Brinell on the forums.
I was planning to get the old head removed and get it tested before doing anything else - then if its good spending the time and money on a refurb.

[Rob Bell]

By coincidence, I was over at Dave Andrews dropping of a head for some porting work.

He has his own portable Brinell hardness tester. Nice but if kit and not destructive. It drops a ball bearing and measures the “bounce” to determine hardness.

He tests around the combustion chambers, particular concentrating around the exhaust side of the head and near the oil channels.

Mine was 110-120, go a good one (relief!) but I was confident owing to the very shallow and narrow indenting of the head by the liner

If your head looks anything like the picture Mykel posted, then it has the hardness of cream cheese and is essentially scrap.

Gerry, not seen that particular product before. Not sure whether it would work or not if the rest of the head were soft, but ideal if there were a lot of casting porosity in the fire ring land area.

[RobboMC]

Hi all,

This alloy of aluminium is hardened in the factory. Softening by over heating usually occurs in a single event. One way to visualize the process is a slippery dip. Some materials have a near vertical curve of softening, others have a more sloping one. In a controlled factory environment it's possible to get an alloy with a sloping curve to 'stop' half way down the slippery dip. With an overheating engine the softening is very much out of control and once the load starts moving down the slippery dip it usually ends up going all the way to the bottom. Like this example for brass.

softening curve.docx

(68.26 KiB) Downloaded 64 times

I've read and heard the official number is 90 Brinell. Rob points out his good one is over 110. Mine head was 55.

If it looks like this:

then it's a boat anchor like mine, don't waste your time getting it tested.

What normally happens is the engine expands with the excess heat of the
'boil over' event and the head bolts stretch. Then when the whole thing cools down and contracts the head is no longer properly tensioned to the block, allowing the liners to move up and down and smash into the head several thousand times a minute. when this happens then the head is scrap.

It's unlikely that a head will have a hardness of anywhere near 90. It will either be good and well above 100, or bad at 55-60.

Most engine building shops that can deal with a K-series engine should have a small testing unit or be able to arrange a test. The result will probably be 'metal or cheese'.

If there have not been any huge over heating events and the surface of the head looks good there's no reason to suspect it's gone soft. Metals don't soften significantly with age. This alloy just can't be heated beyond the normal coolant temperature. For example, my old engine was driven by the PO about 100 miles after ALL of the coolant was lost when the underfloor pipes finally gave way.

A Brinell test will leave an indent that will need to be skimmed off. So normally the head it tested in a few places and then skimmed. BUT it's possible to skim down to a casting defect and make matters worse on a leaking head.

[2woody]

as far as I can tell, softening (annealing) is more of a problem for the cylinder block than it is for the head. In as much as it will allow the liners to drop down a touch, thus not sealing against the head gasket, irrespective of how good or bad the head itself is.

I have a little book with records of the 340 engines I've rebuilt over the years. In all my time, I've never come across anyone who has a hardness tester.

I'm also a little skeptical that a softer-than-standard head is actually not worthy of being re-used, re-hardened or not

[Rob Bell]

This is the cylinder head of a Freelander I rebuilt. Dave Andrews very kindly tested it for me. 110 Brinell on the cold inlet side of the engine. Just 65 on the hot exhaust side.

Academic really:

The depth and the width of the groove really confirmed that this head is cheese...

[Rob Bell]

It was fractionally better than Rob’s though!

[RobboMC]

Yeah i think my previous owner gets the prize for the most overheated K-series in history.

She lived a long way from town and drove all the way without coolant. Amazingly the crankshaft still rotated by hand when I got to it,
shows how tough these things are. Also amazing that it went that far without completely failing. There were only two cylinders with any
compression in the end. Such a waste, just because it was too inconvenient to call a tow truck.

[Mykel]

Looking at the head in Mykel's photo I would suggest that it's "Castleton" (beyond Hope) due to the indentations around the fire rings.

If your head looks anything like the picture Mykel posted, then it has the hardness of cream cheese and is essentially scrap.

Yep, gents, both of you are spot on. Far beyond service.

I like the idea of machining a groove and then fitting a ring to it. Actually when I looked at the cream tart that used to be a cylinder head in my shed I thought, what about cutting a 5 mm ring off an old liner and have that one fitted in there. Would steel be the more sensible alternative? I have no idea. It could be kept narrower in thickness and thus allow for the procedure to be performed on VVC heads as well.

[Kasper]

Gents,I'm seriously diapointed no one knows about Brinell. One of the British metal technologist from YOUR golden age! Well a good education helps

Mykel, in the past we did repairs to engines to get them running on LPG and on the old A's and B's it is done to make them running on lead free petrol by making new harder inserts for the valve seats. it doess't sound strange to me to revive an overheated head in that way! Any old and experienced Dutch car workshop should be able to help you out!

[2woody]

I like the idea of machining a groove and then fitting a ring to it. Actually when I looked at the cream tart that used to be a cylinder head in my shed I thought, what about cutting a 5 mm ring off an old liner and have that one fitted in there. Would steel be the more sensible alternative? I have no idea. It could be kept narrower in thickness and thus allow for the procedure to be performed on VVC heads as well.

Aren't you describing "Wills rings" ?

[2woody]

Gents,I'm seriously diapointed no one knows about Brinell. One of the British metal technologist from YOUR golden age! Well a good education helps

We're well acquainted with Brinell. And slightly more acquainted with Vickers

I'm just saying that I've never seen the test used in the aftermarket for testing cylinder heads

[Rob Bell]

I'm just saying that I've never seen the test used in the aftermarket for testing cylinder heads

Probably not has often as it should be - but as mentioned Dave Andrews certainly does, and I find him a jolly helpful chap to know!

[smmgf51]

Sounds like Dave Andrews has got a Leeb tester from what you described.

Having compared that option it looks like a quicker and less destructive test than Brinell testing. Its one thing testing around the liner area, but it sound like you can diagnose this by eye.

So the numbers for a good head of 110 - 120 - are these numbers on the Brinell scale or the Leeb scale?

As others have identified a number of general engine refurb shops don't even do hardness testing. So if they do its worth knowing what the standard is.

see this link for comparison of scales.

https://en.wikipedia.org/wiki/Hardness_comparison

[Rob Bell]

Almost certainly a Leeb device. Unfortunately, I do not know the scale or units used. I can chat to Dave to find out, but the concurrence of the data mentioned by Rob above suggests that either his head was also tested using the Leeb method with the same units, or that the Leeb data was converted into a Brinell equivalent.

[Parazine]

Regarding the Modus Engine Services solution:

I bought an MGF Mk 1 with a blown head gasket three years ago. I found that the head had some "sinkage" on the exhaust side but more worryingly, small pits in the fire ring area. I dispatched the head to Modus, it was back in a week with the fire ring area replaced with Mykel's rings above. The head had been skimmed and was clinically clean. I fitted it with a Chinese spec head gasket, bolts and new type oil rail. Checked the liner heights, all 4 thou plus. Took my time and rebuilt slowly, all fired up perfectly.
Three years and 6000 miles later, there is no water leakage, no evidence of any problems at all, all running perfectly OK.

I'm more than happy with Modus, a good solution to the problem and worthy of consideration if you have a softened head.

[Rob Bell]

That sounds very promising. May be I won't chuck out those softened cylinder heads after all?

How much did the service from Modus cost, by the way?