All Small Six 170 issues

[awasson]

I just checked the thread and can’t find out about the miles you put on this engine since it was refreshed. If you used iron ductile rings, you need 500 - 1000 miles before you will get them to seat. Were the bores honed and was the ridge at the top of the bores (if any) removed when it was refreshed?

If you add a little oil to the bores when you check you can tell if the compression is lost by the rings or valves.

I had one BMW 4 cylinder engine that took almost 2000 miles to seat the rings after a complete bore and build. I saw a V8 engine once that was refreshed without a hone and without removing the top ridge and it broke the top rings on the ridge.

Andrew

 

[Rodders]

Pu pretty much no miles on it, backed it up and down drive and had it sat idling. Like I said when try to drive under any load it does or can t give any power.
I honed the bores and reemed the lip.

It's definitely coming past rings as air gets in bottom of block during test, I put some oil in cylinder and didn't make any difference.

 

[DON]

 

[awasson]

Pu pretty much no miles on it, backed it up and down drive and had it sat idling. Like I said when try to drive under any load it does or can t give any power.
I honed the bores and reemed the lip.

It's definitely coming past rings as air gets in bottom of block during test, I put some oil in cylinder and didn't make any difference.

Well, yeah, the rings won't seat for somewhere between 500 and 1000 miles. It is entirely expected for the rings to leak. They are 1000 miles away from being bedded. There is a break in process for engines and it is longer for engines with iron ductile rings. You need to drive the car and you need to not expect power from it until they are bedded.

Did you use a break in oil? Also pretty important.

You've might have dodged a bullet by using the original cam. I hope you numbered the lifters and put them back in each lifter location according to where they were originally. That's important because the lifters will wear uniquely according to the lobe they mate with.

If you had replaced the cam and lifters there is a pretty specific break in recipe for that to not wipe the lobes.

Search "break in procedure for ford inline 6 engine" on Google and the AI will give you a pretty reasonable idea of the break in procedure.

 

[awasson]

I have another thought... What year is this 170? Does it have solid lifters or hydraulic. If solids, you might have the adjusters too tight and you're losing compression through the valves not being closed. Still, it needs to break in properly for the rings to bed correctly.

 

[Rodders]

I have another thought... What year is this 170? Does it have solid lifters or hydraulic. If solids, you might have the adjusters too tight and you're losing compression through the valves not being closed. Still, it needs to break in properly for the rings to bed correctly.

Is solid lifters and no air escaping though valves.

Spoke to a local engine shop and they said sounds like I have slightly small pistons if leaking the volume that it is. They seemed like a fairly tight fit... But never done this before so what do I know?? Lolll

Have found another engine locally that going to have a look at.

 

[awasson]

Is solid lifters and no air escaping though valves.

Spoke to a local engine shop and they said sounds like I have slightly small pistons if leaking the volume that it is. They seemed like a fairly tight fit... But never done this before so what do I know?? Lolll

Have found another engine locally that going to have a look at.

If you haven’t broken in the engine (ie: it has zero miles on it) doesn’t it make more sense to break it in property and then see how it responds instead of looking at some random engine?

Right now, expecting fresh rings that haven’t seated to hold compression is a bit like buying a gym membership and wondering why you’re not pumped up before you’ve even worked out. When you break in an engine, everything wears in and sets. That takes time and use.

The rule of thumb is 1000 miles with use below 4,500 RPM but varying the speed. I used to take mine out and drive around areas with less traffic or later after rush hour and I’d find gentle hills or country roads with dips and curves to get a good run at different RPM. When my rings seat, I can usually tell because it seems to have a bit more noticeable power and response. I also got on the highway after a few hundred miles to get it up to speed and use the engine for compression braking. Nothing abusive but the kind of driving I’d expect to do normally. Nothing wrong with getting the engine up to speed and under load.

 

[Frank]

If you haven’t broken in the engine (ie: it has zero miles on it) doesn’t it make more sense to break it in property and then see how it responds instead of looking at some random engine?

Right now, expecting fresh rings that haven’t seated to hold compression is a bit like buying a gym membership and wondering why you’re not pumped up before you’ve even worked out. When you break in an engine, everything wears in and sets. That takes time and use.

The rule of thumb is 1000 miles with use below 4,500 RPM but varying the speed. I used to take mine out and drive around areas with less traffic or later after rush hour and I’d find gentle hills or country roads with dips and curves to get a good run at different RPM. When my rings seat, I can usually tell because it seems to have a bit more noticeable power and response. I also got on the highway after a few hundred miles to get it up to speed and use the engine for compression braking. Nothing abusive but the kind of driving I’d expect to do normally. Nothing wrong with getting the engine up to speed and under load.

Rodders there is another philosophy of break-in when plain iron rings are used which takes less time and is 100% effective in my experience. I observed this method being used when medium-duty diesels were overhauled (semi truck and commercial fishing trawler engines) :
Run the engine easy long enough to assure everything is working right. (20-30 minutes). Then perform a series of full throttle accelerations without reaching the red-line rpm. I broke in a 240 this way last year. Uncoated iron rings. With 2 hours on the engine I went to a secluded country road and spent an hour taking off from a stop, WOT to 4500 rpm, in every gear. (Didn't make 4500 in high gear, LOL, let off @ 70mph.) Stopped and repeat, for an hour. The engine has full compression and has never used a single ounce of oil, used daily, runs great.

I mention this because you have iron rings and have already spent (excessive) time @ idle and no-load. Regardless if you use this method or not, I second awasson's recommendation to get 'er up to speed and under a good load for an hour or so before making a final decision.

PS_ adding oil to the cylinders for a compression test is done to determine if the valves or the rings are the source of low compression. When its rings adding oil does raise the compression. You said the oil didn't make a difference- this proposes that rings may not be the culprit.

 

[bmbm40]

Makes sense to break in as advised at this point what do you have to lose? And buy the other engine for a spare. They are getting harder to find.

 

[DON]

I believe a leak down was done and air coming out the crankcase

 

[awasson]

I believe a leak down was done and air coming out the crankcase

Yes and no difference when oil added which says valves to me

Then again, this engine isn't even remotely broken in so I wouldn't test anything or trust the results until I had put a few hundred miles on it.

Also, I like the break-in method @Frank suggested. I haven't tried it myself but that's how my friends at the bike shop used to break in race bikes for the production class. I bought one of their ex-race bikes 40 years ago and ride it as a daily driver. It's never had the cases split, it's a little on the loose side now but it doesn't even use oil unless I'm relentlessly riding like a hooligan. I used the moly-steel top ring on mine and the rings seated within the first hundred miles.

 

[John Ha]

I like the break-in method @Frank suggested.

But it's so anemic he can't drive it ... it's not possible to break it in if it doesn't have enough power to get up to legal speeds.

I may have missed it, but did it run correctly before you rebuilt it (and why did you rebuild it)? Did you take "before" and "after" measurements of the bores to ensure that you have appropriate pistons and rings? Did you check and alter, as needed, the ring gaps before installing them?