How do I identify the bearing & piston

B

Bipolar Xpress

Mike Gold
sizes in my 1500 engine? I pulled it all apart, and it looks in amazingly good condition. I did a search, but didn't see how to identify if the crank and pistons are stock or not. Can you point me in the right direction?

Also -- the engine had low compression in 3 and 4. 4 would only get up to 90 psi and then quickly bleed off. The head gasket looks perfect and I see no visible cracks in the head or block? Any ideas what gives?

Thanks,
-- Mike/Manchester, TN
 
Leak down test?

Maybe it's not the correct term. What I suggest is using a compressor to pump air into the cylinder and listen for air leaks; if it's loud at the dip stick, suspect rings. If it's loud at the intake or exhaust, then suspect that valve. I hope that makes sense.
 
The back of the big end and main shells will have a part number and maybe a size stamped on the back, but the best (and preffered) method is to measure the journals themselves and compare your figures to the specs given by Fiat for journal sizes.

Pistons are sometimes marked on the top, stock size is 86.4mm in the 1500, scrape away the carbon on top of the piston and you might see a number.. but they are not usually marked as standard, only usually the oversizes, so the same rule applies, measure the bore or piston size directly. (note that the piston is not measured right at the top as this diameter is smaller than the main piston size)

I would be pulling the valves from the head and inspecting them... look for burnt and pitted sealing faces on the valve and seat... but maybe before you pull the cambox do a clearance check... your lash clearance might have been set tight?

Greg if the engines already apart a leak down test won't work :) but that would have been the best test to perform while the engine was still together, certainly much more definitive than a compression test for diagnosis of a fault.

SteveC
 
You need accurate automotive machinists tools to measure the bore and bearing journals, both crank and piston.

Are you trying to add power or just a DIY rebuild to stock? Your intentions for this motor have to be thought about and decided upon before you start buying stuff.

Take the parts to a local automotive machine shop with a good reputation and pay them an hour or two of shop time to measure the important stuff, maybe magnaflux the block, and tell you what you need. The advice of an experienced machinist is worth the price.
 
Low compression

The piston rings can be stuck because of carbon deposits, causing the leakage. Try Miracle oil to free them.
 
Thanks for the input - Where do I find the

specifications? I have the micrometers, but don't know the measurements. I did see part numbers on the main caps, but where do I go for the cross reference?

I have a new head with a 35-75 cam; the inside of this engine looks so good that I hope to just put it back without anything other than ridge reaming & honing. I am trying to identify the bearings & rings I will need -- I suspect stock but that could be an expensive mistake. The nearest machine shop I would trust is about 40 miles away. I trust myself more than the locals.

Sorry for the dumb questions; If this was an Explorer I could be answering the questions, not asking. I just haven't learned Italian yet.

But so far it's been FUN and this board & you folks are the greatest!

I don't want to overextend my welcome, but perhaps I'll put up some pictures of what I have & where I'm going. Planning on driving it on nice days and trying to do some local (read fun) autocross.


Thanks,
-- Mike
 
You wrote, "I don't want to overextend my welcome, but perhaps I'll put up some pictures of what I have & where I'm going."

We wuz gonna ban your user ID if you didn't post pix:nana::innocent::italia:

The online shop manuals seem to have very detailed engine specs. Here are two for later cars:
http://socalx.com/xhelp/shopmanual.htm
and
http://www.midwesternmedicalmachine.com/~damonfg/X_FSM/FSM_index.html#eng

BTW it's my understanding from reading the posts of longtime Xweb members and X owners that the bottom end of the FIAT SOHC engine is the strongest part of the whole car--catastrophic failures and premature wear are very rare.
 
Listen to Dan and Steve... Mike!

Wish ya woulda said something BEFORE pulling that engine down...

I don't wanna spoil your fun... but as George (cozzoi) said... many times we can bring the compression back by just running some ATF down the carb and kinda honing the rings and cylinders.

Alas... you can try that NEXT time...

Do post some photos as they are worth about 1000 words apiece!
 
Thanks DAN!!

The online shop manual!! I'm giddy as a schoolgirl!:excited:

When I calm down I'll take some pix.

Tony, if I hadn't been pulling the engine apart, I would have been mowing the lawn and cleaning the windows, OK?

In any case, I'm glad to know what's inside there. It's really embarrassing to go out & punch it at a stop light and have something important fall out on the ground. (got the T-shirt)

-- Mike
 
I only posted the links, so I can only take a teeny tiny bit of credit. But glad to be of service:excited:

Hats off to Damon and whomever hosts the other online manual...they're the heroes:grouphug:
 
HAHAHA... Mow the lawn or pull the head...

Decisions, decisions...

HAHAHA!

Now what are ya gonna do next week, rebuild the trans?
 
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