I've established that the cylinder head only needs slight repair so intend to replace the piston rather than the engine. A new piston and rings from Toyota is about £200. What other source should I consider? Second-hand?
For new rings it looks as if I need to get a honing tool (whizzes 3 grindstones round on the end of a drill) for "glaze-breaking". Anyone explain? It sounds as if it will deal, partly at least, with the single score line that I can feel in the bore, but hardly see. How will I know when I've done enough with this tool?
- (#12845) Dave Mason (Sussex), 18 Aug 04 09:47
Hi Dave,
in bournemouth there is a place called PRC, Piston Rings and Components. They may have a place near you? or I could checkout the price for you perhaps.
- (#12845) dave Bright (Bournemouth), 18 Aug 04 10:13
Secondhand should be fine. Need to get the right size/ weight class tho. Be careful about getting rings (if you're going to fit a new set)- I've heard of problems getting the correct style for our pistons...
If the engine was reasonably oiltight before this crack appeared, I'd just hone that cylinder, put a s/h piston c/w it's own rings in, and carry on.
When I had this happen to mine, luckily there was no damage to the bore. I just scuffed the bore by hand with a piece of wet&dry and built it up, the replacement rings seated OK. There was no wear ridge to worry about either.
If you want to me technical about the honing, you'd really need internal and external micrometers big enough. But I'm sure if you hunt on the web you'll be able to find info on the average depth of a honing pass.
Oh, and if you're getting a piston, try to get one of the right class PLUS on a con-rod of the same class as your own. Means you can use the original bearing shells and don't have to worry about pressing the piston pin out...
- (#12845) David Miller, 18 Aug 04 11:10
Dave. The "Glaze busting" is a method of taking away the very hard surface finish which is not condusive to the bedding in of two sliding surfaces and does give, to some degree, a better oil retention surface. As David says, and this is entirely acceptable, some minute "scuffing" with a piece of oiled wet and dry, will perform the same function as the proprietary honing devices. With used rings, mating to a used surface, there should be no problem but, some slight glaze busting would help. Personally, I would not worry too much about that minute score in the bore, To try to take it out would bring about more problems and, if a hone were to be used, to eliminate it entirely, new rings might be required to suit the (slightly)larger bore size. I have emailed you re s/h pistons
- (#12845) John Davis (Leics), 19 Aug 04 02:05
If you using wet and dry to break the bore glaze.....there should be info on the best rubbing pattern on the net....the term 'cross hatch' comes from memory....(which I think is X shape rubbing)....worth doing a search before you start
- (#12845) chris turner, 19 Aug 04 05:33
David Miller's "wear ridge" - is that a lip around the top of the bore, potentially making it harder to pull the piston out? It's mentioned in RM025E but I already noticed there aren't any, feels smooth all the way up.
I'm going off the idea of getting a honing tool. I can't see how you can use it to get cross hatch rubbing (to which I've seen reference elsewhere) and I fear that even moving it up and down will take more off the middle of the bore than the top and bottom, whereas wet and dry will be easier to control if it's just a case of roughening the surface slightly.
There is very little in our archives about pistons, but this April Ray East reported his said "No. 1" on top, which agress with Toyota (David Coombs) who want to know is it "1", "2" or "3". I haven't checked piston no. 4 but the front three all have "B" at the front of the piston top. It's not a "3" it's a "B" for Baffling. Can anyone tell me where to search for this "No 1".
And where will the class be marked on the conrod?
I haven't got the piston/rod out yet, I think I may have to start a thread on removing the sump, but eventually, I would really like to "put a s/h piston c/w it's own rings in, [and con-rod] and carry on". A brand new piston and rings seems disproportionately expensive, especially when there must be lots of scrap 2CT blocks around. Anyone point me to a possible source of a secondhand piston+rings+con-rod?
- (#12845) Dave Mason (Sussex), 19 Aug 04 08:27
Hello Dave,
the "wear ridge" I think is caused by the piston rings wearing the lining, so if you can't detect one, then there is no wear, good. The sump removal requires the removal of the cross member underneath the sump, and there is no sump gasket, so you will need some liquid gasket or similar.
- (#12845) dave Bright (Bournemouth), 19 Aug 04 09:49
Size class is stamped on the big-end. I can't find my pictures of my cracked piston to remind me how they're marked tho...
- (#12845) David Miller, 19 Aug 04 11:45
John Davis has sent me a really helpful picture of the piston top markings. I'll publish it in the Ace Handbook eventually.
- (#12845) Dave Mason (Sussex), 20 Aug 04 00:36
Dave, I have some 2nd hand pistons if you are interested.
- (#12845) Mark (Dover), 20 Aug 04 08:07
Thanks Mark. Please email me what markings you have on yours and that'll give me your email address as well. I haven't had a chance yet to look more closely, in the right place, for the markings on mine.
- (#12845) Dave Mason (Sussex), 20 Aug 04 08:40
John's picture guided me straight to the mark which is "2" so at least I have the option of placing an order with Toyota now. This useful picture is now listed as "Piston crown" on the Engine page in the online Ace Handbook.
Dave Bright's contact found pattern pistons for 2CT, but they were not stated to be suitable for 2CT so I didn't ask the price but since realised they might be perfectly fine. Can anyone check if Toyota list the same piston type for the 2CT as for the 2C, or make other comments?
- (#12845) Dave Mason (Sussex), 20 Aug 04 13:53
nope, 2c and 2ct differ. don't know how, but they have different part nos. i'll guess that the turbo engine has lower compression and a stronger piston. certainly the manual differentiates between them, see p em-86.
- (#12845) David Miller, 20 Aug 04 14:52
OK a 2C piston won't do, are 2C rings definitely a different Toyota part number too, because presumably a secondhand piston would benefit from new rings but Toyota 2CT ones are about £100 a set (Toyota 2CT piston is about £100 too)
- (#12845) Dave Mason (Sussex), 21 Aug 04 13:31
Dave, I wouldn't bother replacing the rings. If the engine the piston comes out of is known good, they'll bed into your deglazed bore just fine.
For the record tho 2C pistons DO have a different p/no to 2CT (for 88-92 townies at least...)
- (#12845) David Miller, 21 Aug 04 15:20
My piston is now out. Punched? on top is "B" at the front and "2" to one side. Cast into the side is "3B 64161". So when referring to these 2/3 numbers it may be important to be clear whether you're talking about the top or the side.
I'm inclined to go for a 2nd-hand piston and am being offered some with 64161 and some with 64160. Is this difference important?
- (#12845) Dave Mason (Sussex), 25 Aug 04 03:17
Don't know, Dave. the 64161 looks rather like the second half of the part number, but the cd says 13103-64121, and doesen't recognise 13103-64161.
As we don't know the difference, I'd say yes, it IS important.
It's the "2" that's important according the the magic cd.
- (#12845) David Miller, 25 Aug 04 08:26
Yes, David Coombs, Toyota IOW, confirms today that it's the 2 on the top that he would want to identify it if ordering a toyota replacement.
I should've said that my broken one has "AISIN 3B 64161" cast on the outside. DC thinks it's just a coincidence that the AISIN no. is similar to the Toyota no. (which I thought he said was 13101-64121 but I may've noted it wrongly).
- (#12845) Dave Mason (Sussex), 25 Aug 04 09:15
concerning the fitting of new piston rings ,when rebuilding an A series engine (austin mini ,maxi etc )
to check that the rings are suited to the bore ,you have to fit one of the plain rings squarely (use a piston with no rings on it to push the ring down the bore )the check with a feeler gauge the split gap in the ring ,do this at various points down the bore ,and the sizes given will tell you if there is wear ,and at which points of the bore .Unfortunetly i dont remember the size of the gap ,but if it isnt sufficient then as the ring heats up and expands it will cause the gap to close completely and if further expansion occurs the ring will actually increase in diameter and could cause the piston to seize .
- (#12845) Maddog, 26 Aug 04 01:39
Yes, the Toyota RM025E engine repair manual for 2CT etc describes that process for checking the ring gap cold and says what it should be, but it left me wondering what to do if it's not right. Presumably gap too small - file or grind, gap too large - get another ring. And I guess all the rings must be checked individually.
- (#12845) Dave Mason (Sussex), 26 Aug 04 02:58
This just in from a reputed engine rebuilder ...
"The piston numbering system [ 1,2,3 ] is grading which is only relevant when new. After it's done 1000 miles and run in the bores it is largely immaterial. To allow for sizing tolerances when manufactured the bores are graded and the sizes refer to parts of thousands of an inch difference. The B is also a piston type but more importantly identifies the front of the piston. So ANY piston will do at this stage."
- (#12845) Dave Mason (Sussex), 26 Aug 04 03:29
After 30-40 hours work spread over 5 weeks, some of that just cleaning things up, shopping, and pondering what to do next, my 2CT has rose from the dead yesterday. The final delay, and only real frustration in the whole job apart from the weather, was an iffy exhaust manifold/head fixing.
Having appealed here for advice in several threads, I thought I'd celebrate (I haven't put the floor back or driven it yet, but I'm not superstitious). My mechanic neighbour reckons it's running more smoothly than it has since I bought it over 3 years ago - perhaps because that piston has been faulty all that time.
I really appreciate those who gave me parts, advice and encouragement, especially Mark (Dover), John Davis, David Miller, Jim Adgo and my neighbour. I never intended to do the job myself, just slipped into it step by step, so it has stretched and increased my "Ace" confidence. I'm used to rebuilding things but the nearest I've done to this was taking the head off a Ford 100E (side-valved) back in the 1960s.
The cost? About £275 for head test/tidy up/gaskets and sundry tools and fluids. Another £130 for refurbishing the injectors was really a separate issue. A donated piston saved about £200, thanks again Mark.
- (#12845) Dave Mason (Sussex), 15 Sep 04 03:27