Fiat 1438cc TC - Condition of Block & Head surface

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nilsw
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Fiat 1438cc TC - Condition of Block & Head surface

Post by nilsw » Tue May 02, 2017 9:47 pm

Hi,

I have recently purchased a Fiat 124 AC Sport Coupe from 1967. The car will get a introduction in the Readers Cars section in due time.

The question is somewhat long as I feel the circumstances are important to the problem.
However, the quick version:
- Is the block surface likely to seal with the shown corrosion around the water jackets (see pictures)
- What could be the origin of metal build up on the cylinder head in the quench area (see pictures)
- Is the head likely going to seal, provided it is straight and the ridges are taken off, considering the shown corrosion around the water jackets (pictures)

Now for the long version:
Upon purchase the engine ran fine and continued to do so for the first 300km of the
journey home. After that it started to develop severe overheating issues. Due to the lack
of other symptoms (No blue or white smoke, no appareant oil-consumption, no water consumption when not boiling over)
I nursed the car the remainder of the way home. Upon inspection at home
cylinder 1 showed zero compression on the tester -> The head had to come off anyway.

There is no clearly/visibly broken part (Headgasket, Valve, Piston-Rings) that could be responsible
for the lack of compression. However there are a few places where there is corrosion.
As the head has to go to the machine shop anyway to check straightness (I do not own a long enough straight edge),
I decided to have it cleaned and will rebuild it to prevent future oilleaks or other problems.

Technical Specifications:
- Fiat 1438cc Twin Cam engine, 1967, ~120'000 km
- Uneven Bore spacing (1&2, 3&4 ~7mm, 2&3 ~10mm)
- Engine is stock
- Valve lash as measured (In/Ex) [mm]: 1: 0.35/0.4, 2: 0.35/0.35, 3: 0.35/0.4, 4: 0.35/0.4

Condition:
Block:
- Original crosshatching at top of the bore, no deep scoring
- Corrosion around some water ways, ~2mm deep & ~5mm into the gasket surface (see pictures)
- Rust under the intake between 2&3 -> likely some coolant got out at some point (see pictures)

=> I would like to leave the block in the car and not rebuild it. Do you think the
water jackets are a problem with sealing?


Head Gasket:
- No obvious damage
- Was only doweled at 2 diagonal points (Is this problematic?)
- Slight signs of coolant around corroded water jackets.


Head:
- Cylinder 1 has more carbon build up in the quench area then the rest
- 2 metal ridges/buildups just inside the firing ring of the gasket on cylinder 1 (see pictures)
- Corrosion around some water jackets (see pictures)
- Carbon build up in chambers, both intake and exhaust and the spark plug (I suspect running to rich)
- Very slight pitting near cylinder 1 intake valve/head gasket, possibly from water entering the chamber.
- Valve seats had carbon build up as well

-> My conclusion would be that the head either warped or wasn't seated right from the beginning (ridges), leading
to leakage around cylinder 1.
=> Apart from refacing if necessary (at least taking of the ridges) do you see another problem with sealing?
Are the water jackets too far corroded to be sealed properly? For the valves is simply re-lapping them enough?

Thank you for your help,
Nils Wenzler

Block_corrosion.jpg
Corrosion around water jackets, ~2mm deep and up to ~5mm into the gasket surface at several jackets.
Block_corrosion.jpg (332.02 KiB) Viewed 397 times
Block_rust_outside.jpg
Rust on the outside of the block between 2&3, under intake.
Block_rust_outside.jpg (451.87 KiB) Viewed 397 times
Cylinder1_Bore.jpg
Cylinder bore has no deep scratches and some cross-hatching left.
Cylinder1_Bore.jpg (352.98 KiB) Viewed 397 times
Gasket_corossion.jpg
Gasket shows signs of water/corrosion around damaged water jackets.
Gasket_corossion.jpg (417.06 KiB) Viewed 397 times
Cylinder12_uncleaned.jpg
Chamber 1&2 of the uncleaned head: Water jackets show corrosion. Carbon build up strongest in cylinder 1, especially in quench area.
Cylinder12_uncleaned.jpg (538.95 KiB) Viewed 397 times
Ridges_45deg.jpg
Metal build up just inside the firing ring. What could this come from?
Ridges_45deg.jpg (363.74 KiB) Viewed 397 times
Ridges_side.jpg
Metal build up (Ridges) shown from the side - could be high enough to prevent seating of the head or proper sealing.
Ridges_side.jpg (269.38 KiB) Viewed 397 times
Sparkplug.jpg
Sparkplug with carbon build up.
Sparkplug.jpg (389.08 KiB) Viewed 397 times
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Spider 1969
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Spider 1969 » Wed May 03, 2017 10:39 am

Hi Nils,

Sorry to hear you had such a bad start with your new car! On the other hand you could consider this an opportunity to find out what you are working with and make it better from there.
Some questions:
* Was the car regularly driven before you took over or has it been idle for a longer period of time?
* Apart from overheating how did it run during the way home? If you really had zero compression I would imagine you would have noticed it running on three cylinders.
* Any idea how well the valves on #1 cylinder are sealing?

If the head was warped/wrongly seated to begin with you would have experienced overheating right from the start of your journey home. Personally I would pull the engine, strip, inspect and do a rebuild according to condition found. Head rebuild also takes up a considerable effort and it would be a pity if that does not pay off. But if we can rule out piston ring damage it may be possible to avoid engine rebuild.

Looking forward to your reply.

Kind regards,

Charles
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nilsw
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by nilsw » Wed May 03, 2017 12:08 pm

Hi,

Thanks you for your reply, as to your questions:
- The car sat for roughly a year while being prepared for sale (A lot of regular service work had been performed, eg. new brakes, new exhaust etc.)

- For the first 300km it ran flawless. We are talking mountainous highway in 25+ ambient temperature at constant engine speeds of 4000 - 4500rpm (4-Speed)

- After Bologna, on the highway towards Milan (flat, straight highway) it suddenly overheated violently. I then let it cool and refilled everything. After only
3km it overheated again. As I would have had to call a tow truck anyway at that point I figured I can just as well try and take out the thermostat in order to
try and increase the flow. It actually worked somewhat. Together with the heater on full and the fact that it was getting dark and cooler at that point I managed to drive ~50km at a time without overheating (I let it cool off every major service area to be on the safe side).

- At no point did the engine misbehave apart from the heat. It ran on all 4 cylinders, no rough idling etc.

- No oil consumption, no water consumption, no oil in water or water in oil visible, no blue or white smoke.

- Back in Zurich, after it cooled down, it started to run more rough (however, still starting perfectly from cold) and I measured compression which showed good on 2-4 and nothing on 1. I feel that the compression only really dropped when I started it again a few days after arriving here, as the engine was running notably worse.

- Optically the valves are seated fully, there is also some lash (albeit at the lower end of the tolerances with In 0.35 / Ex0.4). There is carbon deposit on the valve contact area, so I guess it is not seating perfectly. I can however not imagine that it is responsible for the lack of compression. The valves look comparable to 2-4.

=> Maybe having it near boiling for too long overall warped the head increasingly until the seal of the head gasket let go when it cooled down.

As I am doing the work myself in a somewhat limited space and budget, not pulling the engine would be a great relief. The current game plan would be
to redo the head and fit it back on the car without installing all the auxiliaries. Then measure compression again and if it is good proceed to finish it off. If the compression is still not good I am out a head gasket and a set of head bolts. Unless it is anyway likely that these engines need a rebuild at 120k or soon after in stock condition (The car has been very well cared for over all).

Thank you for your help.

Regards,
Nils Wenzler
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Spider 1969
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Spider 1969 » Wed May 03, 2017 6:23 pm

Hi Nils,

To my experience the Lampredi TC can run longer rebuild intervals than 120k km (twice or even more) when driven and maintained properly. Having said that, the head gasket may fail more often and not always with an apparent root cause. Overheating usually is a sign of head gasket failure with or without smoke. Combustion gasses will accumulate in the head leading to diminished cooling effectiveness.

These engines can not be left idle for long as magnetic debris settles in the crank and will be released after start up ruining the bearings. A year is likely ok as I have the experience of starting up and driving fine after one and a half year bodywork being done.

Your way forward does sound feasible with the compression test prior to completion. Question remains where the metallic deposits originate from as your head and piston look ok. Broken ring(s) would have scored the bore and damage the ring lands I presume.

To answer your first questions completely:
* The corrosion around the water jackets is not a problem as long as the gasket is not under cut so do check this after cleaning the deck and the head surface;
* Re- lapping the valves is ok, do check valve stem-guide tolerances;
* The two dowels are standard so no need to worry about this. (Except to make sure that you re-install them)

Further more I would suggest:
* To also check the straightness of the block deck (you probably have thought of this);
* Buy a top notch head gasket, lower cam box gaskets (leak free as opposed to OE and others) and race head bolts from GC. They do assure reliability.

These are my first thoughts so if other readers think different of have additional comments please join the discussion, that's what this forum is for.

Please keep us posted on your progress and I'm looking forward to your car in the racers cars section. The AC is such a nice model and under valued (not only financially) to my humble opinion so keep it up!

Kind regards,

Charles
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Guy Croft
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Guy Croft » Sun May 07, 2017 9:42 pm

Total overhaul and rebuild is a MUST on this veteran, you won't find another easily!

rebore, reface, GC forged pistons (nobody else makes them), head reface, new guides and seat regrind etc etc etc


GC
Guy Croft, owner

nilsw
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by nilsw » Tue Jun 06, 2017 3:05 pm

I just got off the phone with the engine builder I tasked with cleaning, checking and resurfacing the head and have bad news.

There is pitting from cavitation where the small bumps in the cylinder head where. This is right adjacent to the firing ring and
will most likely pose a problem with sealing as it is to deep to get out with resurfacing. Furthermore they say welding can be
tried but would be quite tricky and there is the risk it won't hold up.
They also reckon that it had been welded there before (hence the bumps) and may already have been re-surfaced.
They do a lot of work on TC's in general, but mostly on later 2l and had no data on the stock head height.

Does anyone know how to measure the stock head height and what the factory value would be? (I assume deck to the top of the cylinder bolt hole)

With the new information in mind I don't feel overly confident in rebuilding just the head. It looks like the engine has to come out and be redone
properly. I will get back the head and see if I can inspect the pitting. It might however be necessary to find a replacement.

best,
Nils Wenzler
GC 152

Guy Croft
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Guy Croft » Tue Jun 06, 2017 6:48 pm

Nils

this is GC Q&A

Yes you want a modest budget. Doesn't everyone? This is 2017 - your engine is probably older than you are!

Overhaul this engine 100% top to bottom, in every way, GC style. If you don't know what I'm talking about, buy my 2013 manual, take a long holiday and read it. Then consider how to proceed.

I will tell you - and after all it is my forum, the 3/8 cheap way you are proceeding will result in a box of broken bits that you will NEVER be able to replace!

Whether it's a 1438, 1608, 1592, 1756, 1995 - carburetted or fuel injected, atmo or supercharged or turbocharged, RWD or FWD, race car, rally car or standard car...

I cannot help on cost, good parts cost money and mine - rods - guides - pistons - are the best around. Designed by me.

As I said, this is GC Q&A. Do the rebuild ONCE, do it 100% and right.

Ask anyone on this forum.

Sincerely,

G
Guy Croft, owner

nilsw
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by nilsw » Thu Jun 08, 2017 11:53 am

With the new information in mind I don't feel overly confident in rebuilding just the head. It looks like the engine has to come out and be redone properly. I will get back the head and see if I can inspect the pitting. It might however be necessary to find a replacement.
Well this is what I am saying - The engine has to come out and be rebuilt. However, I will still need a head of some sort and am trying to figure out
if I am better off salvaging the old one or finding a replacement.

So do you know what the stock head bolt hole height is to check if and how much it was skimmed already?
What are your thoughts on welding the caviation damage vs. finding a replacement head? (If used heads on these are often pitted or cracked
anyway, fixing the one I have might be better).

Thank you for your help,
Nils Wenzler
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Rallyroller
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Rallyroller » Fri Jun 09, 2017 9:35 am

Hi Nils
Re cylinder heads, I have a couple of spare 1608 heads. I think they are the same ( may even be bigger inlet valves than the 1438). I may be pursuaded to part with one.



Nigel.
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Spider 1969 » Fri Jun 09, 2017 7:54 pm

Hi Nigel, Hi Nils,

In 2000 I experienced a broken valve on a 1608. Supplier send me a 1438 head which he believed to be the same.
It wasn't as there was no coolant port near the #4 cylinder inlet port. See below pictures, top one is the 1608.

I don't know whether this poses a problem for the 1438 inlet manifold but in that case it dit not match my twin IDF manifold. So something to evaluate before putting a 1608 head on a 1438.

Kind regards,

Charles
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by Rallyroller » Sat Jun 10, 2017 6:20 pm

Hi Charles

That's what I love about this forum. Great insight. Great knowledge.

Nigel.
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nilsw
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Re: Fiat 1438cc TC - Condition of Block & Head surface

Post by nilsw » Fri Jun 23, 2017 1:49 pm

Hi,

First up sorry for the long delay and thank you very much for all your helpful answers!
I wanted to wait with the post until I got a definitive response by the engine builder.
Well, long story short: The head is toast. It has been decked too many times and
will need replacing. My engine builder does have some contacts in Italy which he is
checking at the moment.

@ Rallyroller: From what I can gather the 1608 head should fit the block but has the
difference of the intake manifold cooling as pointed out by Charles (thank you!).
I think switching to the 1608 or an aftermarket manifold should address this problem?
Are you by any chance living in the UK? I will be on holiday there for 3 weeks in July
and would be very glad to have the 1608cc head as a backup plan if we can not find
a 1438cc one.

Thank you,
Nils Wenzler
GC 152

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