Thread: 90% convinced i have a collapsed piston skirt

Tweet

OK - back to engine noises. The valve train is now straightened out so on to the next.

When I started the engine after dumping that set of pedestal mounted rockers, the only 'peep' was a slight bit of roller rocker arm tick and what I've always considered normal and much the same as other engines I've used them on. Spring ahead a couple months, driven the car a fair amount, but an extended run this past weekend has about convinced me that the now returned heavier internal 'clunk' is a collapsed piston skirt and brought about after an overspeed event last year when I tore the motor mounts apart, hanging the throttle shaft near wide open for a couple seconds before I could get it shut down. The oil pressure is fine, and the same as when first started at 65 psig cold, 55-60 hot, so ruled out bearings. My history with Ford 289/302 engines is that piston skirts are weak and clunk, but usually after many hard miles.

This now brings me to pistons. This engine is a Ford Racing crate motor, supposedly with something besides sand cast pistons - but I really do not know what they really are but would bet on the OEM standard cast pieces.

I'll be pulling the engine down, probably starting Nov/Dec time period to do my full internal check as well as pull some or all of the pistons and measure for failure. I've been looking at a set of replacements, and have about decided that the hypereutectics are all I need for what I use the car for and think these might be about the best suited to use without a rebore - KB/Silvolite 3165HC. They maintain an approximate 9 to 1 CR, have double valve reliefs, have the 1.6 compression distance and, best, are reasonably priced for my thin wallet.

Comments? Thoughts??

OOPS! Sorry about 'shouting' in the header

Comments/thoughts???????????????? ok, here goes----you can identify what cylinder is causing noises ny removing /shorting out plug wires one at a time---

Don't buy any parts before you tear it down and find something wrong----------why change a set of pistons for one broken skirt(if that is whats wrong)

How about investing in an oil analysis to see if it's making metal? Here's one place, $25 for the test - Blackstone Labs That, along with Jerry's cylinder-by-cylinder noise check might narrow down your problem, or clarify options?

Jerry, I've done the plug wire removal (the MSD ignition can really light up your day if not careful) and while inconclusive, it's no. 5 and possibly 6 as well(LH side for the Chebbie guys).

Parts - not going to buy anything but the gaskets until sure of what's inside and already have. My concern is if I did over rev and subsequently collapsed that skirt(or two), how many more will just be waiting to go the same way.

As far as broken parts - no metal seen yet in the oil, but might just send off a sample as you suggest, Roger.

What the real gist of my OP is has to do with those Silvolite pistons and if they are decent replacements if necessary, knowing that I will never race it - though will give it some occasional 'exercise'.

For right now - gonna drive it until it gets cold, clatter and all. If it breaks - sighhhhh - that will be the next bridge to cross with this engine.

Not certain of piston skirt failure being the noise although I have seen it only once in a straight 6 Ford. It would only make a brief knocking noise upon accelleration from a stop light...

If your interested. I am going to need to replace the pistons in my stroker block. The ones in there now are .030" over coated speed pro's I think. Not sure if you can use them but, If interested I'll get the numbers. If you can use'em, I'll cut you a sweet deal on'em..

Originally Posted by 34_40

Not certain of piston skirt failure being the noise although I have seen it only once in a straight 6 Ford. It would only make a brief knocking noise upon accelleration from a stop light...

If your interested. I am going to need to replace the pistons in my stroker block. The ones in there now are .030" over coated speed pro's I think. Not sure if you can use them but, If interested I'll get the numbers. If you can use'em, I'll cut you a sweet deal on'em..

Mike - Thanks. I hope to not even have to pull the engine and especially do a rebore. If I do, I can probably find you

As far as that clunk - yep, pulling away from a light or putting it in gear from a standstill and dropping the rpm 50 or so from that 'free' idle brings out the noise. Get past 1000 rpm, long gone.

==========================

Originally Posted by IC2

Jerry, I've done the plug wire removal (the MSD ignition can really light up your day if not careful) and while inconclusive, it's no. 5 and possibly 6 as well(LH side for the Chebbie guys).

Parts - not going to buy anything but the gaskets until sure of what's inside and already have. My concern is if I did over rev and subsequently collapsed that skirt(or two), how many more will just be waiting to go the same way.

As far as broken parts - no metal seen yet in the oil, but might just send off a sample as you suggest, Roger.

What the real gist of my OP is has to do with those Silvolite pistons and if they are decent replacements if necessary, knowing that I will never race it - though will give it some occasional 'exercise'.

For right now - gonna drive it until it gets cold, clatter and all. If it breaks - sighhhhh - that will be the next bridge to cross with this engine.

nothing wrong with silvolites or speedpros (now) or mahle. has a one small one man shop i use over 12 set of just cast pistons a year . they work fine if you fit them . has for your bore if its on the big side they do not like loose .but you can hone the block and get a off size piston s made .i done this on the 4.600 bore stuff . but what is cheaper then that is to go with a 2618 forged piston it will put up with more piston to wall then a 390 alloy. but you need to know were your at know of size .if the wist pin started to freeze up it will take the skirt off in this case piston to wall has nothing to do with busting a skirt

Originally Posted by IC2

Mike - Thanks. I hope to not even have to pull the engine and especially do a rebore. If I do, I can probably find you

As far as that clunk - yep, pulling away from a light or putting it in gear from a standstill and dropping the rpm 50 or so from that 'free' idle brings out the noise. Get past 1000 rpm, long gone.==========================

Ugh.. I was hoping you'd say nope, it happens differently. Anyway, the speed pro's are brand new as are the rings but like I said 30 over. They're not going anywhere for awhile so if you need them, you know how to find me...

As an aside, when I discovered that broken off skirt in the 6 cylinder, I honed the cylinder in the truck and shoved a new standard piston w\rings in the hole and the customer was happy 'cause it was quiet! It never smoked or rattled after that! I have no idea why it broke one skirt.
.....

your engine is a 351W ? i have a new set of mahle cast i think in 030 . have to check to see what i have in the shop if you need something in a piston let me know

Originally Posted by pat mccarthy

your engine is a 351W ? i have a new set of mahle cast i think in 030 . have to check to see what i have in the shop if you need something in a piston let me know

No, Pat, that was my first mistake with this engine. I decided a 351 with the extra width across the head would cause problems so I bought a 302/5.0L crate motor instead.

I know, not smart as I have a fair amount of good experience with 351W's and NEVER a problem - ever

Originally Posted by IC2

No, Pat, that was my first mistake with this engine. I decided a 351 with the extra width across the head would cause problems so I bought a 302/5.0L crate motor instead.

I know, not smart as I have a fair amount of good experience with 351W's and NEVER a problem - ever

i have new pistons for the 302 CH 1.600 i pull them off the shelf see what i have right now i just do not remember .if they were dish and i wanted flat tops with the 351 head i used or there 030 and i needed to go 040 on the 289. anyways i will give you a very good deal on them they do not cost much at the time and more to send back

I don't know fords but can't you pull the pan and look up and see whats busted??

Originally Posted by cffisher

I don't know fords but can't you pull the pan and look up and see whats busted??

yep he could if he want to pull the head and intake pull the bad tooth. put a good one in it with out pulling the engine. hell thats to much bending for me better just pulling it

Pulling that engine just ain't that easy with this car of mine - that's a LAST choice and with this aging body, neither way is easy.

Pat - let me know what you have, SB Ford 302, 4" stock bore/stroke via PM

I went for the last ride of the year (windy and 38*F) and found a few items of significance - the engine still 'rattles', but better, the heater really works well Then, just for some pain, found out that I can't leave the lights on for an hour or so, engine shut down and expect the battery to have any life BUT, I did find that hooking a charger to the starter terminal will boost the battery as long as the master swich isn't off

Oh yeah, that engine? It runs very well - but that low rpm imminent death rattle ....

The engine will come apart over the next few days (weeks?) and one way or another, that rattle WILL go away (probably several $ to many $$$$)