If a 1275 head had a crack in it.

[regularman]

Where might it be? I pulled the head off of my midget today and decided to look for the water eating culprit. It was worse last time I drove it and I could see little sparkly bubbles coming up into the radiator at the first start up. Also pressure building and staying in the cooling system after the car has been sitting for a week or more it will still be there and hiss out when I unscrew the radiator plug. It might have just been a head gasket but its weird. It has always done this since I have had it. I looked for any cracks in the cylinder walls, these are usually pretty obvious. I got another head from Livinginthepast but they both look about the same, not any obvious cracks that I can see. I need to look a little closer when I am in a better mood for this. I am tired of the overheating problem.

 

[Colin8]

Many cracks develop between the two valves as this section is small and subjected to high temperature and stress. One of my heads had a crack like this but I didn't see it until after the combustion chamber was cleaned up and polished while doing a porting job. Cracks are often nearly invisible as they shrink closed when cool. The only way to know for sure if have the head magnafluxed.

 

[RickB]

Yes, magnaflux reveals a lot about a piece of iron.
Sometimes repair is an option in a good shop.
When I had my MGC head done (so many years ago) the place I took it treated it like it was a piece of the space shuttle, when they were done it was amazing. I let it sit on my table a long time just admiring it before I finally put it on the car. Of course I was a bachelor at the time, no wife to tell me that nasty car parts don't belong on the table... :wink:

 

[Legal Bill]

The advice above is correct. The magnaflux will see what the eye cannot. Also, between number two and three cylinders you can develop a crack.

 

[Guest]

Just curious, if you have another head already, why are you worried about this one? Just trying to find the problem or attempting to salvage it if it's still good?

 

[Hap Waldrop]

Kim, get it pressure checked, rather than maganflux, magnaflux is only as good as the human eye can see under the light, and the human eye can't see up into a port. Professional heads shops don't waste their time magnafluxing heads. You hear maganfluxing alot on the LBC forums, but it's not the right test for a cylinder head, but people that magnflux already know that. Not trying to sound like a AH, but you hear magnfluxing throw around way too much for heads, it's jam up crack test for crank, rods, but not a head.

1.31 intake valve 1275 Midget heads are rare to crack, but it happens, the Copper S heads with the big intake valve are famous to crack beteween the intake and exhaust seats, but thats not common on the Midget heads.

If push comes tomshove, get the head down to me, and I'll get pressure checked for you, it it checks OK, I'll show you how to do a valve job and we'll get it or the other one back on the Midget, we have roads to conquer

 

[regularman]

I do have the other head and a new head gasket. I think I am going to put the other head on with the new gasket and see how it does. I already have the stuff so it won't cost me anything. If that doesn't work then I am going bring you both heads Hap and maybe one of them can be fixed if they are bad. I would just love to find the "smoking gun" so I know what the problem was. Could still be the block with a crack somewhere. The head gasket is not the Payen type. I think when I put the gasket on I will use some of that copper spray stuff. I have had real good luck with that on Subarus (famous for head gasket problems) and small ford. I had and old mazda b2000 pickup that blew the head gasket between 3 and 4 and wore a small divet between the two that a paperclip could fit in. I used a new gasket and that copper stuff and drove the thing another 40K then gave it to my dad who drove it another 10K and then sold it on to someone else. I don't know why I didn't think of using that when I put that last head gasket on the midget.

 

[startech47]

K & W Copper Coat Good stuff. Worked well at 13 to 1

 

[nomad]

Before you put the head on check the block deck and the head for flatness. Straight edge and feeler guage should do. Had way to much trouble with A and B serie's engines in that area.
KA.

 

[regularman]

Before you put the head on check the block deck and the head for flatness. Straight edge and feeler guage should do. Had way to much trouble with A and B serie's engines in that area.
KA.

I did that last time with a machinists straight edge and a gauge, but I will do it again to make sure. One other thing I am going to do while I have the head off is put me an up top timing pointer on there. Its real easy to verify TDC with the head off :wink:

 

[nomad]

As my kiwi relatives say "Good on you" Kim. Makes sense.
KA

 

[regularman]

OK, well. Change of plans. I got up early this morning and took a good long look at both heads. The one I took off I did some more cleaning on and checking and straight edging and got it out in the sun and checked it all over. Dang if I can see any crack in it. On the other one I need to a least lap the valves and put some new valve seals in (which I though I had but don't have). Anyways, after looking over the original head, the block and the old head gasket, I feel the most likely cause is a head gasket leak in the number 2 and number 3 and that nearest water hole area. There seemed to be a tiny amount of pitting around that water port and the gasket looked different there than between 1 and 2 or 3 and 4.
I decided to put the old head back with another new had gasket and this time used the permatex copper gasket spray that I have had good luck with in the past. All back together now and I fired it up and ran it for just a couple minutes. No more bubbles into the water for now nor any oily foam on the water.
I got some more work to do before a test out. I need to pull the steering column back out and replace that broken shroud around the switch area and attach one of the newly acquired Harley mufflers to the back instead of the straight pipe.

 

[Hap Waldrop]

Kim, get a black composite Payen head gasket, Gordon at the B Hive (Clemson, SC) has them in stock, and can get to you next day for regular ground prices.
He should have valve seals in stock, as well, if you get the whole head kit, it comes with seals, exhaust gasket, and the works.

 

[Guest]

if you get the whole head kit, it comes with seals, exhaust gasket, and the works.

It never hurts to have spares ready to go.

I think I have more parts in my house than on my car.

 

[regularman]

Kim, get a black composite Payen head gasket, Gordon at the B Hive (Clemson, SC) has them in stock, and can get to you next day for regular ground prices.
He should have valve seals in stock, as well, if you get the whole head kit, it comes with seals, exhaust gasket, and the works.

That sounds like a plan there Hap. I got my fingers crossed on this one.

 

[regularman]

While the head was off I made an up top pointer for the timing out of spring steel. Its no thicker than a coat hanger but stiffer. Anyways, I put that on and made a marker for degrees out of masking tape and put it on. After putting it all back together and running it, I see that the good spot where the car runs the best is about 25 degrees static. Way ahead of what is recomended. I have the DGV which might be the reason for that. I tried setting it down around 8-10 degrees and its way too retarded, won't even idle. I spent the day playing around with the car and hope to drive it some tomorrow to see how it all works out.

 

[Legal Bill]

Kim, get it pressure checked, rather than maganflux, magnaflux is only as good as the human eye can see under the light, and the human eye can't see up into a port. Professional heads shops don't waste their time magnafluxing heads. ...

Very interesting. I did not know this. The machine shop I used for decades from the 60s to the 80s (last time I regularly used them) magnafluxed the heads. They often found cracks, but I can remember getting back a couple of heads that failed due to an undetected crack. 80% of the work they do is high performance across a wide range of engines and applications, from autocross to drag racing. I'll have to ask them if they pressure test now. How long has pressure testing been in wide use?.

Not being able to see up into the ports with magnafluxing does sound like a problem though. Have you seen a lot of cracks in the ports?

 

[dklawson]

As a footnote on crack detection, I used to work for a firm whose main product was built from ductile iron castings. We used both dye-penetrant and Magnaflux for crack detection. The dye system often worked quicker and found small cracks that Magnaflux would miss. I have had occasion to try either on cylinder heads though.

 

[Hap Waldrop]

Kim, get it pressure checked, rather than maganflux, magnaflux is only as good as the human eye can see under the light, and the human eye can't see up into a port. Professional heads shops don't waste their time magnafluxing heads. ...

Very interesting. I did not know this. The machine shop I used for decades from the 60s to the 80s (last time I regularly used them) magnafluxed the heads. They often found cracks, but I can remember getting back a couple of heads that failed due to an undetected crack. 80% of the work they do is high performance across a wide range of engines and applications, from autocross to drag racing. I'll have to ask them if they pressure test now. How long has pressure testing been in wide use?.

Not being able to see up into the ports with magnafluxing does sound like a problem though. Have you seen a lot of cracks in the ports?

Pressure chacking has been aropund longer than either of us Bottom line magnfluxing is all about using a process to let the human ey check for cracks, if a crack is deep inside a port, how is the human ey goign to see it, but a pressure chack puts the head under the exact liquid pressure it would be while operating, and if they is a crack water will leak out the crack. Now thay are some case that pressure checking will not show a crack, if a crack is say in a valve seat, like they do on MG heads, then eye and magnafluxi checking is still a good method, but in Kim case, pressure checking is the way to do it. I pay $35 to have heads pressure checked and found crak sunbig this methos in race heads where magnaflux failed. Also it worht noting, just because you can buy a die test kit these day and knowing how to use was is two different things, just looking at a magnfluxed piece and detecting the crack is a skill, not a given. Basicly it takes a understanding on how cracks originate, when looking at magnafluxing, there are several conditions that could confuse the tester into thnking he is looking at a crack when he is not. Pressure checking is fool proof, no skill required, it pressurizes the head with liquid,and if there is a crack it will elak, palin and simple. To be honest with you, I never heard so much about magnafluxing heads until I started hanging around LBC forums, it for sure it not the preferred method among good shops,and leaves alot of room for error.

 

[Deleted member 8987]

PT really came into it's own with aluminium heads.
Magna-Flux doesn't work too well on aluminium.

I Mag them first.
I have seen too many "cracks" not open until engine is hot.

PT if it passes mag (if you want something you can really, really rely on).

I remember an engine (not Brit) with freeze cracks down the inside of the pan rails.
Passed PT.
Guy rebuilt it, assembled it, ran flawless, until it got hot, and dumped ALL the coolant into the pan.

Happens.

In the shops, Datsun, Honda, Nissan, all the new cars, head gasket goes, yank it, PT, and mill.

But, they are all aluminium.

I remember a couple of Chebbie thin-wall V-8's, all the PT and Mag in the world couldn't find the crack between the oil pressure ports and the water jacket, but you get it warm, and oil starts coming out the overflow.