Cylinder head repair

[ObedP]

Hello everybody.

 

This is my nightmare: some month ago I had a blown head gasket. It was due to a leak. Took it to the mechanic. They took the cylinder head to have it machined flat. The result was as I show in the pictures.

 

 

 

So put new head gaskets and everything was working fine.

 

But two month later the engine started to heat up, specifically since two days ago. I noticed the temp gauge needle going up almost reaching the red lines. What I did was stopped the car and let it cool down a little bit and then continue driving. So the engine didn't heat up to the extreme. I parked the car and I have not been using it until I have it checked by a mechanic. But yesterday I was checking the coolant level and it was really low! But I have no leaks. So it is being evaporated. Also when removed the oil cap, found coolant/oil mixture white stuff!!

 

By reading a very good post between Ricardo, Wino and fpga, I learned a lot about properly working and installing a cylinder head. Also learned that the mechanic missed some steps you mentioned like cleaning the valves, testing for leaks, and some other details. You mentioned about a guide Ricardo will realease soon about woking with the cylinder head. That would be really helpful for me as would like to show it to the guy that will do the work.

 

My question: looking at the pictures I posted, was the flattening work on the head properly done? I still see some holes, kind of deep. I suspect the head needs more work or maybe it was wrong assembled, or bad head gasket. The engine did not reach an extreme heat level this time, but why the head/ head gasket failed to manage such temperature level? By the way, the heating problem came up after replacing the spark plugs and cables. I got the cables wrong installed a few times, the car refused to start, but later I finally put the cables in the right order and the engine started fine. However like three days later the heating problem develops. 

Edited 5 June, 2016 by ObedP

[ObedP]

Adding two more pictures.

 

 

 

 

[jonnycilia]

the cylinder head is not machined all the way flat it still has spots where its uneven and let coolant pass. it must be a mirror finish

[areed]

There are lots of pictures, and plenty of info, in the thread where I replaced the headgasket on mine: http://www.briskoda.net/forums/topic/379717-felicia-13-cylinder-head-corrosion-around-coolant-ways/

 

Mine also still had corroded patches after flattening, as can be seen in the thread, but it has yet to show any signs of failing after 6 months so I think that is fine.

[RicardoM]

ObedP,

 

My first advice is strictly bureaucratic. Your car is subject to many repairs. It is a long, interesting to watch project. I had already expressed my positive opinion on your determination to keep a Skoda Felicia alive. Given the complexity of the project, I invite you to do a little housekeeping of your topics. Right now the members of the forum can't have an easy to follow, complete view of your work to your car because it is broken into smaller topics without having some sort of "main body" or "index of jobs". I suggest creating a new topic titled My Felicia - Index of repair jobs. Describe your car then start listing chronologically all repair and maintenance jobs you did and why(!). If a job has been discussed in this section of the forum, insert a link to that topic.

I remember your topic titled How can you tell if thermostat or water pump are faulty? You narrowed down the cause of overheating to only two possibilities right from the start. That was a mistake. Overheating is a phenomenon with a multitude of reasons. But I can understand your opinion. You simply hoped your biggest nightmare doesn't come true... Sadly, that didn't happen.

 

Now, about the head or head gasket failure.It is not very clear when the last two photos were taken. Was it after the first HG failure? All I can tell for now is pistons 2 and 3 had been cleaned by steam. That suggests coolant leaks in those cylinders.

 

A HG can fail from:

• low quality HG
• low quality head resurfacing
• uneven torque of head bolts

A mechanic can find the truth by "reading" the failed HG. Do you still have it? Post high resolution photos of both sides. Now about the quality of head resurfacing. It is not mandatory the surface of machined head has a mirror finish. It is more important there are no faults around oil and coolant passages. If you look again at first six photos, you'll understand where are the weak spots.

 

I have also these questions about cylinder head machining:

• Was the head just corroded? Was it warped too?
• How deep was the head machined?
• Was it impossible to shave more material for fear of pistons hitting the valves?

[ObedP]

Thanks Ricardo for the suggestions. I will do the little housekeeping of my topics to have them in better order.

 

About the HG: the last two pictures were taken after the first HG failure.

 

After I had the cylinder head refurfaced the first time, the temp gauge was always between 70-80C, sometimes during a very hot day it would reach 90C at some time. True, that is not a normal behavior for the temp gauge. But it was after replacing the spark plugs when I started having the heating problem. I was driving the car without problem for like two months before that. Temp was ok. Coolant wasn't evaporating. No white smoke. My point here that I suspect it was due to the head not have installed properly. Also the guy applied engine oil to the head gasket, front and back. To the two of them. Is it needed? I think the oil will prevent a good grip between the two parts, as it is formulated to withstand high temperatures. Am I wrong?

[RicardoM]

Smearing the HG with engine oil is an old trick used by old mechanics to prevent rust and for easier removal of old HG at next HG job. However, unless specifically recommended by the HG manufacturer, the HG must be installed dry. I can't tell for sure if that contributed to HG failure but I can tell that swapping sparkplug leads can shock the engine hard. Don't quote my on that but I'd say it's 75% mechanic's fault and 25% yours.

[KenONeill]

Ref #1, all that pitting in the head should have been removed, but that leaves me wondering whether doing so might have planed the head below its limit, which causes problems with compression ratio, and possibly with valve gear geometry and hence timing on a "cam in block" engine.

[felicia16v]

It's already past the max skim depth as the indicator is gone.. (small indent in the face manifold side in halfway along.)

Possibly be OK as it's carb so can retard the ignition to stop it pinking. Only other "fix" is filling the holes with something before skimming in chemical metals or weld.

[felicia16v]

At a guess there is not enough support around the middle cylinders as there looks to be fairly deep pitting there still. Oil on the hg wouldn't help either though.

[RicardoM]

...the indicator ...(small indent in the face manifold side in halfway along.)

You mean this one?

Edited 7 June, 2016 by RicardoM

[felicia16v]

Yes that's the one. Skoda said that was the service limit for refacing when we were doing the headmaster's.

[felicia16v]

Doh headgaskets not headmaster's

[ObedP]

Will it work if I use a product like JB weld or Gunk to fill the little holes? Or do you know of a better product? Then brush the area to make it even with the head surface...I think that would be better than reface the head again. I know that even better would be to buy a new cylinder head, but I just can't afford it.

[areed]

Will it work if I use a product like JB weld or Gunk to fill the little holes? Or do you know of a better product? Then brush the area to make it even with the head surface...I think that would be better than reface the head again. I know that even better would be to buy a new cylinder head, but I just can't afford it.

 

If you use something to fill the holes, I think you would need to get it resurfaced in order to get the head properly flat.  Could you get a used one from a breakers yard maybe?

[ObedP]

I saw this site: http://www.enginebuildermag.com/2015/04/engine-block-and-head-repair/

 

Which metod of repairing do you think may work with the Felicia's cylinder head? By the way, what is this cylinder head made of? Aluminium or cast iron?

[areed]

I saw this site: http://www.enginebuildermag.com/2015/04/engine-block-and-head-repair/

 

Which metod of repairing do you think may work with the Felicia's cylinder head? By the way, what is this cylinder head made of? Aluminium or cast iron?

 

The Felicia cylinder head is aluminium, as is the engine block.  I honestly have no idea about ways of repairing it, sorry!  Skimming the head was enough for mine, so I never looked into it.

[ObedP]

 I can't buy an used head as I would have to do the same with it. Also it cost $130.00 dollars. Kind of expensive for me. I can't resurface more as it would affect the distance needed between the valves and the pistons. Do you have any idea what can I use to fill the holes with? Tig welding seems like the way to go with aluminium, but it is expensive. Some have used something called "epoxies" like this one:

 

Devcon Titanium Putty

High-performance, non-rusting titanium-reinforced epoxy engineered for making repairs to machinery and equipment that can be precision machined. Withstands heavy loads in hard chemical envirnoments.

KEY FEATURES

* Excellent temperature resistance (350°F)* High compressive strength (18,800 psi)* Resistance to chemicals and most acids, bases, solvents, and alkalis* Qualifies under Mil Spec MIL-PRF-24176C, Type I

I think that as the filled holes are not so big and they are located under the head gasket, the titanium stuff will be pressured down, adding more grip. Some folks have done this and they say they have been driving for years after fixing this way.

[RicardoM]

ObedP

You got numerous good answers so far. But all are too expensive for you because the initial corrosion was too deep. You can't do much with a cylinder head still badly pitted around middle coolant passages after such deep resurfacing. I don't think anyone can guarantee for success after using any type of miraculous epoxy. You are on virgin territory. In my opinion the cheapest solution is to buy a new head now. Everything else will be just a temporary fix and you'll end up where you are now but with even less money in your pocket.

[jonnycilia]

in my opinion a new cylinder head is the solution, it wasnt that much when i bought mine only 120 euros. and a second hand one was 80 euros so went for the new one.

[ObedP]

Please don't dismiss this idea as soon. Check out this product: http://www.jbweld.com/products/highheat-epoxy-putty 

 

Also please check this site where some guys have tried this method: 

http://www.jalopyjournal.com/forum/threads/i-need-a-product-to-fill-pits-in-an-aluminum-head.786577/page-2

 

I know that as Ricardo says, it is virgin territory. I think it is not going to remain virgin anymore. The pits where I will apply it are only two and are located beneath the head gasket which will be pressuring down hard. So I think the risk is minimum. I think that there is more risk on leaving the current condition as is as the coolant would slip easier because the hole will make the surface of the gasket uneven in that area.

 

About repairing a cylinder head, it is not something so horrendous as it may seem, if someone knows what is doing.

Check out this video about repairing a cylinder head with aluminium welding.

 

Now the fixing work in the video I consider myself kind of not trustworthy as the part welded will be exposed to constant movement of the valve and explosions that may cause the part welded to crack and fail.

But that is not my case as the area to be filled with the JB weld is protected by the head gasket pressure action. Some have also combine this work with a product added to the coolant in the radiator which then adheres to the head gasket sealing any possible leak on it. 

 

This is in deed way more cheap that buying a new cylinder block (around $360.00 dollars here in my country, Dominican Republic). If anyways this fail, I won't be wasting too much money and then I would consider buying an used, good-condition head block, and have it tested before buying it. 

Edited 9 June, 2016 by ObedP

[RicardoM]

We don't dismiss any solution. It is you that dismissed them for lack of money. Aluminum welding - no. Second hand head - no. New head - no. You are about to make the same mistake just based on your "I don't want that bad thing to happen and it won't"  false hope. You will end up with more problems trying cheap 'fixes' on a cylinder head. Trust me.

[ObedP]

Yes Ricardo I know. But is it either leaving the car parked for some long time until getting enough cash or trying this fix. I am not dismissing anything, it's that right now I just can't. Of course I would love to buy a new head. Do you really live in DR?? I will keep you posted on this if you are curious enough to see the results. You don't know if this prove to be something worth knowing about, be it for good or bad.

[Breezy_Pete]

I've never tried such a repair on a HG sealing surface, but I have done with success on pitting around coolant flange areas. I suspect the HG environment will make such a repair as you're suggesting short-lived; but that might be months rather than weeks/days?

[RicardoM]

I will keep you posted on this if you are curious enough to see the results. You don't know if this prove to be something worth knowing about, be it for good or bad.

I am curious and I would love to see that your experiment proves to be a success. The only problem I have with using epoxy is that a cylinder head is subject to tremendous shocks and temperatures. We are talking about containing rapid explosions for years and years! Previous head gasket failed simply from a few backfires when you swapped two sparkplug leads.

 

A realistic expectation of your experiment would be to buy you enough time to gather some cash while still using the car.