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Discussion Starter · #1 ·
Hi folks,
Found out today that the crankshaft on my GT may have to be replaced or have the connecting rod bearing seats polished (possibly built up and reground) as well as the caps. Evidently the PO didn't grease these before reassembly.
Here's the question. Didn't see cranks listed on Opel GT Source. Do they carry them or am I looking at repairing my crank? I'm betting that no matter what I'll be better off doing one of the above rather than looking for a crank from another GT which would be a chance at another that would need all the same attention. Got an opinion and/or answer.
I really would appreciate any replies,
Ging (just a tad teed off about now...)
 

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Ging;
You might have to have yours redone, but, anyone from a 1900 motor will work, as they are all the same. I have a spare one here if you run out of options.
Gene
 

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OPEL-LESS!!!
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70 and older cranks are forged, 71 and newer are cast. as Gene said any one will work, but they are not all the same in that aspect. forged is heavier, but stronger, cast is lighter but weaker. both withstand the stock redline just fine.
 

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Discussion Starter · #4 ·
Thanks and pictures

Thanks for the great advice. Gene, I'll keep that crankshaft in mind (it's a great offer). should things go wonky. It's also good to know about the specs on those cranks; I confess that in most cases I prefer 'stronger' for that just-in-case scenario.
One other question. Think polishing will require larger cap bearings? Take down the metal too much?
Thought you might like to see the actual damage so check out the photo.
Thanks again,
Ging
 

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Discussion Starter · #5 ·
Pictures!!

Okay, I'm trying this again.

Well, I can't get the file attachment to do whatever it's supposed to do so just check my member album; I'll put it there.
Ging
 

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boomerang opeler
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hi ging
they look like they will regrind and then you only need undersize bearings to match the new size
BUT check if you can get the bearings first as they may be hard to find!
any local auto machine shop will be able to sort it
just give it all a good wash out with kerosene (dont know how you spell it there we spell it paraffin) as there can be grit and swalf in the oil ways that you must clean out even if the shop says its done , better safe than sorry (happend to me with a lotus engine and it was $880 a set for bearings @ the time but @ least the shop payede up as they had cleaned it on the bill)
 

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Do you know why your bottom end went bad? Was in run out of oil?

You might wish to determine why the crank went bad before you fix it.

Garry
 

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Kalifornia Kid
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I do hate to correct people. However the below statement is not true.

"70 and older cranks are forged, 71 and newer are cast."

ALL 1.9L engines had Forged crank shafts.
Rods for the 1.9L are Forged up to around sometime in 1974 & 1975 engines.
The cast rods are much thicher then the forged versions, as they must be to have enough strength.
Dennis
 

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Dennis: dont want to start a pissing match, i hate those, just where i got my info from....

read somewhere on here that the 70 and older were forged, 71 and newer were cast. my personal experience with 4 CIH engines proved this to be true by ways of the "Ping test". had a 70', 71' and 2 72' motors, all four never been torn apart. the 71' and 72' cranks "pinged" when you tapped the flyweight with a light hammer, while standing on the cement floor with the flywheel attatched. the 70' crank sounded like a "thud". more like bustin your buddy sittin next to ya in the shoulder with a hardcore slug...lol. anybody else have info on these? i'm curious now.
 

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All the 1.9 cranks are forged, but as Dennis said the late rods are cast ('74-'75).
 

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OPEL-LESS!!!
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what would cause some of the cranks to ping while others sounded like a thud when i taped them with a hammer? something to do with the flywheel maybe?
 

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i hope the crank that "thuded" isnt cracked, i mistaken that for the only forged crank i had and i used it in my 2.0!!! runs fine, i have 50 miles on it before i had to have my pistons shaved.
 

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ging, here's my 2c's: the crank dosen't look that bad. Have a shop do .001 turn on it and get a set of .001 oversize bearings. It looks like small sand cuts to me. Unless your crank is cracked, I would go that rout. MUCH cheaper and it trues it up. Talk to a machine shop.
 

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Old Opeler
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Cleanliness .....

Looks like the bearings have been subject to dirt or grit in the oil or left in the oil holes in the crank after grinding. If it has not been run too long most of the damage will be to the bearings so it is worth polishing the journals to see if they clean up within specifications then use a new set of bearings - after everything has been scrupulously cleaned. Dismantle the oli pump and remove all oil gallery plugs and use rifle bore brushes to remove ALL grit and grime. Clean it and flush it with slovent till you think everything is spotless ..... and then clean it some more.

It depends what size your crank has been ground to - worst comes to worst it may mean another regrind or another crank.
Have a serious talk to whom so ever assembled the engine:mad:
 

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Have a shop do .001 turn on it and get a set of .001 oversize bearings.
To my knowledge, rod bearings for the Opel CIH engine are only available in 0.25 mm (approximately .010", or ten thousandths of an inch) "under-size" (the journal is ground to a "smaller" diameter, versus cylinders, which are bored to a "larger" diameter, or "oversize"), 0.50 mm (approximately 0.20"), and 0.75 mm (approximately 0.30"), while main bearings are also available at 1.0 mm (approximately 0.40") under-size.

While it would seem that the bearing shell wear that I see in the picture is quite excessive (I have posted it below), only a machine shop can tell you which under-size bearing you are going to need, since the crank grind process not only takes out the grooves in the journal, but is also used to "true" (straighten) the crank. Take your crank, along with the spec's from a Factory Service Manual (found on page 60-58, table 60B-7 in the '71 FSM, page 60-37, table 60A-4 in the '72 FSM, or page 6A-31, table 6A-48 in the '73 FSM) to your favourite machine shop, and they should be able to help you out. You might also consider taking your block (with the journal caps), pistons and rods at the same time, so that they can check everything for proper alignment and tolerance. If the caps are stretched or worn a bit, they can be "re-sized" (where the ends are ground down a bit and the holes re-bored and, if necessary, align-bored) to ensure that you don't just spin a bearing after you go to all this trouble

HTH and good luck
 

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i hope the crank that "thuded" isnt cracked, i mistaken that for the only forged crank i had and i used it in my 2.0!!! runs fine
Jared, PLEASE tell me that you had your crank magnufluxed before you re-assembled your engine. Or at least visually inspected by someone who knew where to look for cracks at stress risers and such. Did you get your crank ground during the re-build? If so, they will have checked it out.
 

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Ging:
Is it possible the engine was started without the oil pump being primed? Non-Opel mechanics may miss that important step. Another possibility to add to the mix is the rod caps were mixed up and didn't get assembled to their original rod.

I agree with Old Hippie and Kwilford, take it to a machine shop. They may be able to polish it or turn it down for an undersize bearing.
 

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Keith: when i did the rebuild, i had a machine shop turn my crank, chamfer the oil journals, and clean the oil journals, been running it now and then in the barn with 50 previous miles before i shaved my pistons, i think its OK, i'm thinking maybe it was something with the flywheel, maybe the bolts werent tight or something so it didnt vibrate like the rest.
 

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Discussion Starter · #20 ·
Well, I am just completely -what's the word?- grateful! Can't begin to tell you how much I appreciate all the great advice and tips. Particularly all the preventative checks to have the machine shop take to make sure I cover all the bases. I am NOT keen on the idea of having to dismantle this all again in the event something else is a problem as well.
Gary, I think the cause was a lack of lubrication upon the 'first' start after the rebuild. Another mechanic had a look, said he had seen this sort of thing before and that was almost always the reason. Unfortunately I believe the PO did exactly that. As GTJim said, I intend to have a serious conversation with him. It's just negligence in the above scenario and I didn't go out of my way to do all the research and questioning to buy this sort of problem. Who would ask that? And GTJim also gave me a lot of good advice on the cleaning. After seeing this I'm inclined to agree wholeheartedly. ;)
Keith thanks for the great info on the machine shop needs in the way of specs, info, and questions I need to ask. Particularly having the caps checked. Don't think it would have occurred to me until too late. I'm very interested in what you said about looking into the true of the crankshaft. I'm interested in all of it!

Can't thank you all enough for the fabulous information and the benefit of your experience. This site and it's members are the absolute best and may end up saving me a lot of money and time.

Now I've just got to look into bearings. Oddly enough I just picked up a set awhile back on the 'off chance' I'd need them. Mmmm, makes you wonder if that whole precog/divine intervention is working hard. Maybe it was just my little purple beast telling me subconciously that it needed these things. Hope it continues. :))
 
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