mg tf 160 bad head gasket

 
Hi All! 

I bought an MG tf 160 to learn how to fix cars knowing it had a bad head gasket. I've taken it apart and noticed that the bottom piston has a slight chip (see images: The lower piston ring barely shows through the chip).

 
I am tempted to put it back together as I am on a slight budget but I'm worried it might spiral into a bigger issue in the future and all the work would've been in vain. 

I would greatly appreciate some of your thoughts

many  tanks 

-Max
 

Hello and Welcome...

Do Not put it back together!! 

That is almost certainly why the HG failed.
You would be wasting a new HG, time and money for it to fail 5 miles up the road.
Check the bore to see if it is scored...the very minimum you can get away with is a s/h piston and replacing all of the other rings. 
I built Toyota engines and kept spare pistons but I knew they were good and not oval so I got away with it.
That's a big job for a "novice" and I say that respectfully.
Others will offer advice soon.

Ring around the specialist breakers such as 'Bitz to see if any have a usable 2nd hand piston and con rod. Best to read up to see whether youll need to drop the rear subframe to remove the sump or whether that can be done with the engine in situ. Its a bit of work but quite achievable and it shouldnt be expensive on parts if you use a 2nd hand piston and so long as there's no damage to the valves or the bore.
Whereabouts are you ?.

Max..
What mileage is on the engine? 
Is there a service history showing regular oil changes etc?
Did the previous owner explain how the HG failed? He wouldn't know about that piston.
Any other problems mentioned whilst chatting about the sale..like knocking noises?
As has been said it could be a relatively "simple" fix but it could also be a long drawn out saga..building it back up and the big ends knock..or it smokes..etc.etc.
I'm not being a downer Max..I understand a limited budget but it's a tricky one to answer.
Not being your car before it broke means you can't know how good the engine was running before hand and unless you knew the seller you can only take his word for "how good it was" before the HG went.
If it has approaching 100k on it then bite the bullet and re-shell and re-ring it and lap the valves in etc. You will really learn a lot from that excercise!
Clean that bore out with petrol and really check if the bore is scored because if it is it's a rebore...
I'm new to the K series engines but others can advise on the cost of a known s/h short motor..or even a complete motor.
There are some reputable dealers out there known to this forum.
Good  luck!

Ok that piston is buggered! There is a bit to do to replace it,  it's gonna be a engine out job. the bore is probably damaged too.
Have you rotated the crankshaft whist the head was removed, without anything to secure the bore liners in place? I ask this because the bores can move if not held in place. on these engines when the crank is turned without something to hold the bores in place, this can cause all the bore liners to not seal properly at the bottom and for them to have an  uneven height making the head gasket not seal properly.
this isn't gonna me the cheap fix were hoping for!

Download the workshop manual free from this site.

Where in the world are you? If your in the UK, your cheapest course of action is probably going to be find a good second hand engine.
What's the rest of the car like? I ask because it the whole car may end up  a money pit if it's a rust bucket.
At the very minimum your are up for a S/H piston, new rings, the gasket set, timing belt etc.
You'll probably find that you need to replace the bore liner too, and find that as you go you may need to replace bearings, head bolts, water pump, do some head work, etc.
Price these items before you go much further, I'm not trying to discourage you but if money is tight then you need to assess if it's an economically viable project for you.
I would hate encourage you to waste your time and money on a shitbox that isn't worth it. But if the rest of the car has potential, then maybe it's worthwhile.


You are asking questions in the right place, and we will help walk you through this, but you need to know if it's worth your while.

 

Thanks for all the great advice guys! makes working on the car less daunting.

to answer all the questions:
- I'm Located in South Africa (parts aren't super easy to come by but doable, and one can order things from Rimmerbros)
- the car has 136,000 km on it and the body is rust-free and in pretty good nick.
- There is no service history, but I heard the engine running(purchased for about 900 pounds so was willing to risk it) and It couldn't hear any obvious issues and started up easily. There was just an issue where it would stall once it got up to temperature. Quite strange in that it would idle fine, but then I would apply throttle and once it tried idling again it would stall.  
- I believe the HG failure was caused by one of the coolant pipes leaking fluid till the car overheated.
- I haven't rotated the crankshaft since removing the head (great tip)

I've already done some work on the cylinder head and am rebuilding it after skimming it and lapping there valves(watching lots of videos to make sure I don't mess up the timing and making sure it's within the head height limit)

 After reading all the messages I'm convinced to go ahead and remove the pistons to asses the damage and at minimum replace the damaged one and all piston rings. Will post my progress/findings here



 

Seeing as you're not in the UK, then the good 2nd hand engine is probably not an option. Still at least your like me in Australia so won't have the rust horrors that most of our Pomgolian friends have to endure, so although we might have to freight our parts over but at least our cars don't turn into a pile of orange flakes with some glass, plastic and rubber bits sticking out of it, before our amazed gaze!

Hi Max...your second post gives us so much more information!
Firstly your location and that you have a rust free car. That makes a huge difference and means it's worth doing the engine right.
Secondly your skill level has been elevated due to the work you have already done!

I would take the engine out and strip out the pistons, replace the broken piston and re ring them all. Take out the big end shells and inspect the crankshaft journals. They don't have to be "perfect"..there maybe very fine lines..as long as it's not grooved. The bearing shells will give you a good indication.
If the car is good it makes sense to do it right first time. It keeps the car original and you know you will have a good engine you will look after.
I'm good at building engines, gearboxes etc but I know nothing about these engines specifically..but guess what..there are guys here that do! They can answer very specific questions and will get you thru it.
Good luck!

Welcome to the Tbar.

Something else to consider is where did the pieces of piston material go to? 🤔What additional damage, if any, has been caused?

I'm not sure what the shipping would be to SA but good used 160 pistons are available with matching cylinder liner for sensible money  https://www.mgfntfbitz.co.uk/shop/160-vvc-piston-k-series-engine/

Finally got around to removing the piston and can properly see the the damage, was actually pretty straight forward  . Struggling a bit to get the liners out so I'm soaking them in penetrating fluid. 
It's got the number "135" stamped in the side. Could this be a piston from a 135 engine?(or are they the same and it doesn't matter?

 

 

 

I'm wondering where the bits of broken piston ring have gone ,the missing bit of piston are soft so they might not do much damage before they get blown out through the exhaust  if they were small pieces, but piston rings are hard, and I'd expect to see some damage to the top of the piston and the cylinder head if chunks of piston ring were bouncing about in there.
I wonder if some ham fisted ape hasn't broken the piston installing it,  and pulled the lose bit out before bolting down the head and hoping for the best.
What does the bore of the liner look like?