Thinking of rebuilding the '85 2.5 engine. What bearing/piston sizes to choose? (Page 2/4)
Lou6t4gto DEC 09, 01:24 PM
you MAY be" better" off buying your Parts Separately. that way you can get the BEST. Clevite or King Bearings, perfect circle rings, "coated" pistons. Do not buy Cut Rate cheap Gaskets !
cebix DEC 10, 05:45 PM

Originally posted by Lou6t4gto:

you MAY be" better" off buying your Parts Separately. that way you can get the BEST. Clevite or King Bearings, perfect circle rings, "coated" pistons. Do not buy Cut Rate cheap Gaskets !

That sounds reasonable. How would I go about that? I've only seen "full" kits and not parts sold separately. Are they even available to find under "fiero" and "parts"? Or should I just measure all around buy non-specific Fiero parts?
Iain DEC 11, 07:06 AM

Originally posted by cebix:

I'm thinking of rebuilding my 2.5 engine and want to order a rebuild kit but they all require main bearing, piston and rod bearing sizes. How do I tell which ones I need?

Anyway my car is an '85 but just to be sure how can I verify exactly what engine do I have?


No one has asked the most pertinent question.


What makes you think it needs a rebuild? You haven't posted any compression/vacuum/leakdown/oil pressure results.

I have been accused before of coming across like God when discussing building engines. That's because I've built more than a few, and seen well meaning people tear down a perfectly well running engine 'that needs rebuilt' when it doesn't. Half the time they end up wrecking the thing.


cebix DEC 11, 03:29 PM
That's true, I haven't done any of these tests. There are just some symptoms that I only assume are mechanical wear. It may also be some negligence in maintenance but it's so tough to troubleshoot since so much stuff was done. And I still drive it everyday.

All I know is from observations - that it consumes oil, spits it out to the air filter area, starts poorly when cold, blows a lot of white/blue smoke when cold and when restarted hot for a few seconds. Has a rough and uneven idle when hot. Also it loses coolant with no visibile spill other than the reservoir will blow out sometimes some coolant when it's full. Oil looks "clean" as in no coolant contamination but it has a LOT of carbon buildup when I remove the valve cover. Mileage is I'd say pretty average for an automatic - I get around 28 MPG highway (65-85 MPH) currently when it's wintertime and we have ~30 degrees Fahrenheit on average.

And it hasn't done any of that a few years before. 2 to 3 years ago I rebuilt the ingnition and fuel systems so I think I can get those out of the way. If there are things I can check before rebuilding it - what would I do that would tell the most other than cylinder pressure? I would gladly make some tests to avoid a rebuild. Thanks.

[This message has been edited by cebix (edited 12-11-2018).]

Red98422 DEC 12, 01:10 AM
IMO a compression tester is a vital tool for determining engine health, I know you said “other” than that but truly it is very important.

That being said what do your spark plugs look like?
Iain DEC 12, 06:19 AM
do a vacuum test if I were you. A compression test will not tell you as much if that's the symptoms you're having. If you don't know any mechanics with one, ask any motorcyclist friends, they use them for balancing carbs. Download a guide from the Web on how to use one. Gives a very accurate condition of bore wear and let's you know if you have any valve or head problems.
I suspect you may have a blown or leaking head gasket. They don't always cause the oil or water to mix. They can leak water into the chamber, which causes uneven running, water consumption and white smoke in the exhaust
cebix DEC 13, 04:49 AM
I think I'll just buy one. Will this type do the trick?
Iain DEC 13, 10:37 AM
Yes, that will do it. run through all the tests it will list in the instruction.

Vacuum tests are generally a little more sensitive and can often be informative than compression testing, since the engine is actually running when you carry it out.
You want a nice steady vacuum reading at idle with no fluctuation.

I have a friend flying over tomorrow, I'll see if he has space for any parts I have lying about. no use to me
Iain DEC 14, 04:51 AM
Sorry, didn't get home until stupid late.

Something an old bloke taught me which may help.

Loosen and clean the threads on the plugs before the vacuum test, reinstall, but only tight enough that they seal. Get fully up to temperature. Conduct all the vacuum tests in the instruction sheet/card and note the readings as you do them.
Let the engine idle a couple of mins.
Switch off and remove all plugs as quickly as you can.
Watch for any steam coming out of the plug holes. Because the coolant system is up to temp and pressurised, water will be forced into the chamber if the gasket is leaking slightly. Doesn't work if the gasket is leaking badly enough that the oil and water are mixing, but can be quite spectacular if only a slight leak into the chamber.

Do make sure that all the manifold hoses are clear of residue.
Red98422 DEC 15, 06:05 AM
Ok so maybe I’m not understanding.

Where I’m from a vacuum test is a gauge you hook up to the base of the TB or carb to test the vacuum of the engine, it’s usually used for tuning pourposes, not engine general health. It’s the same gauge you use to setup multi cab setups on an outboard (well familiar with this).

However from the additional comments you made it almost sounds like you are talking about a leak down test?!?!?!?!

If you don’t mind could you explain in more detail for your friends in the US? Simply confused as to what you are suggesting for a test procedure...I’ve heard of doing a vacuum test on an engine before, however that was specific to a two cycle engine to crank case seal and reed flutter.