Rebuilt engine "tight"??
 

My 2.0 engine has 300 miles since rebuild. It has the early sand cast aluminium casing. Since rebuild I have trying to address the issue of operating temps. It has been getting up to 210F. My mechanic has checked many things (so I will not provide a list).
Anyway, in checking out the engine the other day he found that while the crankcase would turn easily by hand when the engine was cold, this was not the case when the engine was warm. If he tried to do this after the car had been running at 190+ the crankcase was very hard to turn by hand. (apparently nearly impossible)

Not being very knowledgable about this, I have no idea why it is getting harder to crank the car in such a manner.

Could anyone tell me whether this represents a problem or not? Is there something that could have been missed in the rebuild?
My engine rebuilder said that the case wasn't milled or anything and to the best of his memory it was all within specs. (note: it was rebuilt a long time ago).
Oh, and also, after my mechanic checked the case and corrected a few things, etc the engine has no oil leaks and only leaked a drop or two a week anyway.


Fred:confused:

I dunno here ..............the guy said it would 'turn easily by hand when cold'?? Then very difficult when warm? That just doesn't make good sense. At 300 miles the rings haven't completey seated as well as a host of other metal to metal surfaces. I don't think that 210 is something to worry about unless after 1200 miles still runs warm.

Just a couple of guesses. Does the car have mechanical chain tensioners? Maybe they're set too tight and are binding up the chains when the engine gets hot and expands. Maybe your mechanic is mistaking the higher compression feel of a hot engine for being "stiff".

-Andy

Eagledriver - you are right, the car does have mechanical tensioners. Thats a very interesting suggestion. I don't think we had thought of that.

I seem to recall John Walker saying this is what happens when the cases are warped, but perhaps this was just in reference to magnesium cases. You might want to do a search of previous threads by JW.

It probably has to do with the motor expanding and no slack in the chains to make up for it.

If you measure the motors width when cold it is less than when warm. Even more so when using aluminum cylinders.

A warped case will induce drag on the crank whether hot or cold.

Why mechanical tensioners?

the tensioners are solid or "mechanical" on the advice of the engine rebuilder at the time (and I really wasn't in the position to know other alternatives). It was a long time ago - 1991, with the engine sitting since then and never fired up until 3 months ago. To do the carrera ones it requires the covers be remachined, etc. I got a quote to do that now and it was a whopping $2,700 AUD or $2100USD (labor and parts). Anyway, it is not uncommon here to use the solid tensioners on early 911s due to this issue. Also, if you ever want to sell it, going with solid looks original (I guess). Here, at least, the logic I have been told, is that other than a re-check and adjust every 10,000 miles, the solid ones are ok.

Fred

This is going to be difficult to diagnose as you would have to get the engine hot and then pull the tensioners to determine if it is crank or cam. I'd be tempted to put in a pair of non pressure fed tensioners (certainly I not continue to use mechanical ones, they'll trash your chains way before the non pressure fed ones will fail)

I have a pair of new ones you can borrow if it will help (you pay freight from NZ)

Neven

Neven, thanks for the offer, but I think we should do some trouble shooting first. I guess, if it makes sense, we could just loosen the existing chains, (as the tensioner is adjustable), and then retest. If the crank still tightened up when we got the engine warm, we would know it wasn't the tensioner.

the early cases usually don't have a problem with the mainline getting out of true. have the guy pull the plugs when the engine is hot and see if it turns over better then.

Fred

No prob, 210F is pretty normal in traffic esp in summer, the other thing to check is if it gets stiff as the cylinders heat (before the crankcase is hot) then it could be a piston/ring probem

Where are you in Victoria?

Neven

Definitely pull the plugs before checking... As mentioned I suspection tensioners... Could be too tight either from the collapse collars or something else. Also are you using a non OEM piston like the old JE's? Could the piston be scuffing/expanding?

Does the starter sound lazy or struggle to crank it when hot?
Maybe it just has real low compression when cold

Chris, He has the solid tensioners.



Here's a jpeg of the safety collar. The picture is with a 901 tensioner as opposed to the 930 tensioner which is the better way to go with the later style idler arms with bushings. Which by the way shouldn't be overlooked as the idler is just as important to the equation.http://forums.pelicanparts.com/uploa...1109884882.jpg

I will find out more tomorrow.
NevenM: it appears that there are two schools of thought with these early small engines in regard to temps. Some people say they should run btwn 180-200F while other say warmer. It would appear that the early temps experienced by these cars were probably not the best as Porsche both put an oil cooler duct in the alternater shroud and a front cooler with no displacement increase between '67-'69.

Cstreit: The pistons are Mahle - purchased from Porsche. Since the rings are not seated yet, it doesn't seem to have high compression that its fighting. A compression test the other day gave 125-135 all around. That probably has more to do with the S cams.

911MOT: it starts like any carbed car does when hot - nearly straight away if left for a short time but longer if it has had a little time to cool off. It turns over fine, and I think the delay in firing up has more to do with the Webers.

Your last post has me thinking it's perhaps a starting system issue. If the engine is very difficult to rotate by hand, the starter will reflect this as well (difficult to crank), but you say it starts okay (longer cranking when warm). Are you sure your tech said he tried this with a wrench on the pulley?

Sherwood

I saw the car today and walked through things. Based on talking with my mechanic, the tightness isn't out of the ordinary and is more a function of being such a fresh engine. So, I probably overreacted. It is true, it doesn't catch or anything when turned with a wrench, just a little tight.

Actually we have the engine out of the car at the moment due to the temp concerns. We decided to change the original alternator shroud and change the fan pulley size. My mechanic located and installed a later T shroud (repainted red) that has the grey tunnel bit for the oil cooler. The original shroud ('67) had virtually no room (or minimal) for air to be pushed down over the cooler. The new fan, combined with the higher fan speed, should cool the engine more (our hope).

I would be curious to know if other people had also "upgraded" their shrouds from early cars to ones with the cooler duct and what results they got.

I saw the car today and walked through things. Based on talking with my mechanic, the tightness isn't out of the ordinary and is more a function of being such a fresh engine. So, I probably overreacted. It is true, it doesn't catch or anything when turned with a wrench, just a little tight.

Actually we have the engine out of the car at the moment due to the temp concerns. We decided to change the original alternator shroud and change the fan pulley size. My mechanic located and installed a later T shroud (repainted red) that has the grey tunnel bit for the oil cooler. The original shroud ('67) had virtually no room (or minimal) for air to be pushed down over the cooler. The new fan, combined with the higher fan speed, should cool the engine more (our hope).

I would be curious to know if other people had also "upgraded" their shrouds from early cars to ones with the cooler duct and what results they got.

The later shroud definitely makes a bit of difference to getting more air over the cooler. Adding an additional cooler will do you no harm either.

Cheers

Fred

What were your termperature concerns (how high did it go)

Neven

Unless the engine has radical, go-fast internals, they say the magic number for an external cooler is 2.7 liters. Yours is 2 liters. Does it have high comporession? 5-blade fan and slow pulley? Hot heat range spark plugs? Retarded ignition? Does it see high revs continuously? Is the ambient air temp. high?

210ºF is quite normal. I wouldn't worry about oil temps. unless they consistently hover around 230+ºF.

I suggest breaking it in first, then see where you are before proceeding.

Sherwood

Sherwood,
thanks for the pointers - no radical go-fast internals.

My engine has only got up to 210F or so (212F when it was 95F outside). Having spent the time and effort on it (or really money), I got a little concerned when I had people telling me it should run cooler (and more than one). On the limited driving I did do, though, it really showed that it could easily run cooler. I found this out by taking up a winding small mountain road when it was about 65F outside. It got up to 210F but when I went down the other side it shot down to 180F. But the other day in traffic it wouldn't come down from 210F even when I got some open stretches and revved up to 4,000. This lead me to believe that a little more cooling could make it run nice and cool (not too cool). And you have to remember that I am thinking of this prospectively, when I really will let it go (post run-in). This is where the shroud with the duct idea came from as the engine cooler hardly gets any blown air in a '67 stock config.
The ignition has been everywhere and making things difficult. My distributer is a little tired at 37 yrs. and has been sent away to be rebuilt. Then I will be putting on a M&W ignition system to go with it.

The tensioners checked out fine also. They are the original spring ones that were converted with a kit to sort of solid. At this point I am going to leave them as is.

But you are right, I just need to drive it at this point.

Fred

Your temperature behavoiur sounds fine to me, I drive my 73 2.4E daily in traffic and 180 is 'warmed up' but 200-220 normal for driving in traffic, It sounds high but you have to remember 212 is 100C and most modern watercooled cars run their oil at 90C (194F) so for an air/oil cooled engine its fine, Hot would be prolonged periods over 220.

When I'm open road cruising the range is 190-210 depending on how fast i'm going

HTH

Neven

NevenM,
open road cruising in NZ sounds great. I had been living in the US for the last decade or more to come back to Oz and find that traffic congestion here has really become a problem (in the city of Melbourne). Just to get my little car out on the road takes 30-40 min of crappy lights and stop and start stuff.
Temp wise, I was hitting 210F when it was 20-25C outside, which is not too hot (ambient tempwise).

Fred

Yes but aren't you amased at how well an early 911 behaves in traffic, My 911 had been off the raod for 10+ years and I was worried that I wouldn't be able to use it daily, but i can.

I've never been to Melbourne but have just organised a long weekend in April there. Hope its as good as everyone says.

Neven

Fred999 check your oil t-stat, mine was bad and I jumped through alot of unneeded hoops becouse of it, BTW Porsche put an externaly oil coolers on all S's at 2.2L. I live where it gets hot and like to flogg my car. I went with one also even though I have a 2.0L s I figure 200cc is not that much of a buffer considering Porsche might not of planned for really hot places:cool:

Neven: hope its warm then as its freezing at the moment (ie early 60s or 15C).
ficke: checked the t-stat. It was ok. I hear what you say about the external cooler. Hopefully I will not have to do that after the shroud change. BTW, did you put a later shroud on your car before putting on the external cooler?
Also, I checked out a 2.0L 1969 S the other day and it was fitted (original) with a front cooler, so I guess it was earlier than the 2.2s (once 2L got the MFI, I think).
Although Sherwood stated that 2.7 was the magic number for an external cooler, didn't Mr Anderson use the number of 170hp+? Then this would catch the 2.0L S model with MFI (I think) and definately the 2.2.

210° is normal. not a problem.

Fred , 69S's had external cooler?s:eek: I guess my 200cc buffer is not as much as I thought. Yeah I read in Bruce's book that 170hp was the porsche determing factor. I did not put on a newer shoroud sounds like a good idea, thanks. My engine is apart right now getting piston oil squiters, by pass mod., and a Carrera oil pump plus a new intermedate gear that is the reason for this tear down.

I saw the piston squirter upgrade in the book but I thought it was recommended for going to 2.7 P&C? Your upgrade certainly sounds like you are being cautious. Did you do the engine tin mode too?

Fred

There are big debates on this one, The fact that it is mandatory for nikasil P&C ie 2.7 upgrades as they run a closer tolerance than Cast Iron or biral cylinders but it is a worthwhile upgrade for pre 2.4 engines as it significantly drops the piston (& cylinder) temp. Having said that I wouldn't pull your engine apart to do it

HTH
Neven

I duno if it has been mentioned but I would get rid of mechanical tensioners ASAP - they do not compensate for different engine temps and thus wear out your chains very fast. That's why they do need very frequent adjustment. If you have a race engine that comes apart after a couple of races well that's a different story.

Ingo

At 140.000 mile oil started to look like well used trans oil only instead of bronze it was silver. The tin was cut before but that was not enough. I figured while it is apart I will do these upgrades. I really injoy these SWB 2.0L S's they really are a streaight shot of 911, not watered down, and am not looking for a diffrent feel so I just am updating it to the things Porsche found to help. The only "back dating" maybe a small hp gain I am doing is twin plugging the heads in an effort to take advantage of the early design. Frankly I hate having the lower valve covers cast for the plugs and not machined :mad: they look like they were left half done:confused: That is proably the dumbest reason to twin plug but there is some others, pass emmision, burn 91 octane, cool heads, I do not have the later carbs with the inrichner,etc. I also really agree with Ingo and went with later chain box's so I could run P-fed tensihiners. I know it will not "look right" but this is one of the first cars I am really building for me and the peace of mind is worth it:) I wish I was where you are, sorting out the car instead of waiting on a machine shop:D