Engine Rebuild Suggestions & Tips Needed

Whew! Can't imagine what the estimate is going to be.

My suggestion would be silicone water hoses and some upgraded material on the timing chain tensioner.

 

Been there: small overhaul, then add a few while you are there and my car is still stuck after 7 years (still waiting for the distributor to cross the pond before Brexit). Not so much of an issue as I love to tinker with it and in the meantime my brother was kind enough to let me play with his 365. To be perfectly frank whatever you will buy will need to be adjusted to your specific engine and every single part is going to be a challenge. You've been warned!

• If you can avoid messing with the block, crankshaft and bearings, do yourself a favour: don't !
  
• Replace timing chains
• Replace dodgy timing chain sprocket. If your system relies on the older style sprocket, you will have to replace the whole set as these cannot be mixed (as a bonus there is less chain wear with the newer ones).
  
• Replace chain tensioners
• Check support ref 100200 for any crack
• Check cylinder heads for cracks
• Replace sodium exhaust valves. You can put new sodium ones if you fancy originality, but do not take a chance on old sodium valves
• While you are there just install new guides and stem seals
  
• If from time to time your starter makes a "clong" sounding noise, rotate the flywheel starter gear by 180°. This will require to drill a new hole for the locking pin and the flywheel will have to be balanced again.
• Perform a complete overhaul of your cooling pump (bearings etc...)
• Replace the cooling pump exit water hose as this one is hard to remove once the engine is back in the car
• if you are after performance upgrades, time the car as per the 412 owner manual (~4° more overlap). If your car is a carbed GT, not applicable obviously, but then you may consider the 365 camshaft profile (?).
  
• Upgrade the firewall and manifold heat-shields
• If your manifolds are rusty, it's time to invest in these. While you are there, you can upgrade the exhaust to the 412 style (3 sections per bank instead of 4)
• Change the airducts that are under the windscreen pilar: these are a pain to replace, so better to do it while the engine is out
  
• Upgrade the k-jet distributor seals to ethanol compliant ones. If you have carbs, refurbish them with ethanol proof seals
  
• Replace the fuel tank filter screens
• Change the airconditioning hoses, as these are "somehow" easier to install when the engine is out (no need to remove the whole dashboard, "just" the right leather panel of the central console)
• If your car does not have the additional oil coolers and third cooling fan, just upgrade your car so as to match late 400i gen1.
• Modify the battery tray so as to accept 90Ah battery (need to remove the spacer that's soldered on the tray).

I've made quite a few more upgrades to mine that would make a perfect "Don't Do It" list...

 

Before jumping into the expensive overhaul have you checked the oil risers seals? Some coolant in the oil is more often than not related to this cheap seal.

 

Yes, be sure to change the o-rings that sit just below the oil filters. I think that is what raemin was referring to, but normally when they leak you have oil in your coolant. Also, check/change motor mounts and every seal and gasket.

Now take or leave this one. I needed a new timing chain and tensioner. Thee are lots of forum posts about changing he timing chain; it certainly does not require pulling the engine. Unfortunately, changing the the tensioner requires pulling the engine in order to get the chain cover off the left side of motor. I don't have a design for it but a good mechanic/machinist could modify the tensioner pivot and the cover plate so that the pivot could be removed through the cover plate. In the current "design" that pivot is captive inside the cover. If a new hole was precisely drilled thru the cover plate which would be sealed with an o-ring or copper washer and the pivot was modified to unscrew thru the hole and from the front of the block it would become a very easy job to change the tensioner without pulling the motor. I don't know anyone who has done this, anyone?? If I was in the shop that did my job, I would have supervised the "upgrade". I know in Maranello pulling a motor is no big thing, but just to change a tensioner??!!

Good luck with the rebuild. Raemin had lots of good ideas.
Ken

 

Yeah, that tensioner is a real problem. I don't know anyone who has gotten one out with an engine in.

 

This???

 

You replaced the timing chain tensioner without pulling the engine?

 

“I” is not really the real guy... But looks like my mechanic is about to. As I am not a mechanic and dont speak a good english neither, could you explain/show me on blueprints what is supposed to make the engine out necessary, so ask could ask my mechanic??

 

La langue n’est pas un problème, c’est pourquoi Dieu a inventé Google traduire!

Il semble être de notoriété publique que le guide de tension de chaîne (la partie à qui la flèche rouge pointe) ne peut pas être changé avec le moteur dans la voiture. C’est un article d’usure qui doit être changé.

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My shop started the job thinking they could do it without pulling the motor. Maybe they could just raise it a bit..... Cover would not come off until engine was out. Roger if your shop does it please have them take pics and post them. Merci.
Ken

 

Thanks for the tip, Dave! problem is, when it comes to technical language google becomes a bit random... and as I don’t even have the words in french it makes it tricky!

All I know for sure is that my engine is now as you can see on the picture and that the engine did not come out.

As I had read threads about it and so I thought engine had to come out I told him I was (happily) surprised. He just answered “we managed”... He/we think that if the job has not been totally done like it was supposed to is precisely because they did not manage.

I’ll ask him about that part and how he did.

Well, the job is not finished and the engine not running yet. I hope he is not too enthusiastic and presumptuous!!!

 

Under normal circumstances there is more pressure in the oil system than in the cooling, so oil is more likely to find its way than coolant. However there are a few situation when the coolant is under higher pressure: 1/ during startup, if both filters and the radiator are dry it may take a bit of a while before the oil reaches the oil risers 2/ when the engine is extremely hot the oil pressure can get fairly low if stuck in the traffic, and that's typically a situation when coolant is under pressure.

So, yes, I would change these O-rings, change the radiator pressure caps, flush the oil twice (cheap 15w40 dino oil) and perform another oil analysis after 500km.

One should reluctantly tear apart a Colombo, on the basis a single oil analysis.

 

One analysis isn't enough. I ran an aviation lab that specialized in oil analysis and the golden rule was trends. I'd run another one in 2,000 miles and look for change.
Look at it this way; if the engine really is in coming apart the extra 2,000 miles won't really matter.

 

Good day Daren,

I fully agree with Dave. This is no different than repeating a medical test if the first indicated a serious concern. It is always possible that the initial test was done in error or your and another sample got mixed up. Engaging in such significant work almost necessitates a double or triple check before proceeding.

Cheers,

Sam

 

"I did have the water pump seal, related oil seal, and brass impeller changed recently. Also, the test sample was taken from the very last drops of oil in the pan as we almost forgot to take the sample until the last minute."

I worry about the water pump rebuild which could lead to water loss into oil and maybe the source of the metal if not done right. Clearly the last drop sample is not representative.
Ken

 

If you have a noticeable coolant leak I would be finding out where it's going before putting anymore km on it.
Coolant leaks can be very destructive to bearings and cylinders.
After engine shutdown heat soak holds pressure in the cooling system for a while and if you have a leak into a cylinder this coolant can cause corrosion to the liner before next startup.
As others have said it could be the O-rings under the oil filters but if you are not seeing any oil under the radiator cap it is unlikely.
Remove all spark plugs and pressure test the cooling system to make sure no coolant is leaking into the cylinders.

How many km are on the engine and is it regularly driven?
The engine I'm working on has 68,000 miles and the two end conrod big end bearings are worn through to copper (these are the last to get oil on startup) and all other bearings look OK.

If you do have to go down the engine rebuild path also check the water/oil pump chain tensioner as there are two versions of this as well and mine had one with a plastic body that shattered during engine disassembly.

Cheers,
Al

 

A couple more suggestions. If the headers are in decent shape get them ceramic coated on the inside and outside. I’ve been very happy with my modern gear reduction starter. When the engine is out go thru the engine compartment with a fine tooth comb. It’s a great time to look for rust. Also replace the flexible duct hoses for the fresh air. You still might not be able to replace the hoses on the side with the brake booster but the other side should be done. Also if you need any front suspension work especially the steering box this is a great time to look at it. My engine had a rebuild. New bearings with a polish on the crank. Same pistons with new rings. Also I went with all new stainless steel valves with new guides and I had them do new valve springs also. If you need new pistons there are much better pistons available today then there were when these cars were built.

 

Hey Jim, where did you source the duct hose? I'd like to replace mine. Thanks.

 

In general, when pre-assessing “needs” for potential overhaul or rebuild, rather than using years, I’d be more concerned about the (engine) mileage after its last major service or overhaul and which parts were reconditioned or replaced at that time.
In other words, how many miles since the engine was fully disassembled & overhauled/rebuilt and what exactly did that operation included (Same would apply to any other running gear and mechanical area/component/part of the car, like transmission, suspension, steering, rear end, brakes, etc)
And if no clear records exists and car/engine potentially has more than 30K miles (45-50K kms) since any major overhaul/rebuild, I’d plan/prepare for a worse case scenario.

You may also want to look at the "Engine Rebuild" thread on "Vintage (365 thru GTC4)" section for general expectations & reference, as the basic principles and engines discussed on it are quite similar and most will apply on one discussed here. (Sorry, I don't know how to provide a direct link to it).

To paraphrase one of my favorite quotes, "There are rebuilds and then, there are rebuilds. One may not have much in common with the other."

 

Aside from last rebuild and mileage, let's also consider the sort of usage the engine had to sustain. No doubt my own engine did need a complete reconstruction, but on the other spectrum my cousin has been babying his 412 for 2 decades: he makes all the maintenance on his own, long winter storage, waits 1/2 hour for the oil temp to raise prior to hammer the gas pedal, AGIP only lubricants (good or bad?) etc... The car is well past 100.000km, works perfectly smoothly, valves were only adjusted once!