I fancy rebuilding my engine.

[shirubaby]

Now before you say dont do it or what for...let me tell you that this proposal is for the spring/summer when the weather is better (i hope).

My engine is from a 1989 300ce coupe which is a SOHC straight six. I am planning to save up and spend around 400 to 500 pounds in parts.

With the help of my mate who is mechanically minded, we reckon we can get it done in 4 days.

However I am not sure what I should spend on; to get replaced.
Certainly, piston rings as on my list. Perhaps replace the oil pump. Head gasket and head bolts, of course.
BUT what else?

Currently, there is a lot of blue smoke coming out of my exhaust pipe (only when I accelarate hard). No smoke when slowing down. The smoke also smell funny. And the plugs are covered in oil. So not a good sign.
I've just put in Castrol GTX high Mileage oil in the car in the hopes that it will cut the smoke down. MOT due in April, and I'm worried that it'll fail it's emmisions.

But hey, it's all there to try us

I need your thoughts on this matter. Especially from people who have rebuilt merc engines. And pints for people who can give me advice on this particular engine.

What are the parts that I need to buy (gaskets, seals, etc.)?
Are there any companies that sell a complete rebuild kit?
Can I get oversized rings and fit them in by gently filing them down to the bore size?
Would I require a rebore?
What else should I be thinking of replacing?

If things go well, then I hope to place a long howto on this forum. Might help others.

Cheers in advance
Shiru

 

[Bolide]

Engine rebuild

I'll take a punt here and say that when you strip your engine you'll find that the valve guide oil seals are worn (new seals and possibly guides needed), the cam, followers & tappets will be perfect, the timing chain will be OK, the tensioner will need replacing (on a "might as well" basis), the engine bores, pistons & rings will be fine and the crank will be fine but you'll replace the shells. But, re-reading your post, maybe more is worn and you'll need a rebore & oversize pistons & rings, which will be £££

You'll burn through more than your budget when you add exhaust manifold bolts & gaskets, serpentine belt, water pump, tensioner idlers and possibly oil pump as you replace bits that "might" fail

I'd give the block, crank & head to a company that can degrease & measure them, check the bores for wear & ovality, check the crank for wear, grind the valves if needed and possibly skim & pressure-test the head

I am told that it is _very_ easy to snap the camshaft when removing it so I'd leave it to someone who's done Merc engines before or someone who, at the very least, knows that this is a possibility

I'd also allow 4 weeks and double your budget to avoid nasty shocks!

Nick Froome
www.w124.co.uk

 

[television]

Re building engines in an MB follows standard engineering.

If you are stoped with the engine running for a few mins and then pull away,or rev engine up,if it smokes, its valve guides worn. Worn valve guides will oil up plugs, as will worn rings/ bores

When you have the head off you can see the condition of the bores.
I think that you will find that you only need new valve guides, an easy job.

If you need any advice when doing it just ask.

Do you have a compression tester, if yes you can determin what is wrong with that.

malcolm

 

[shirubaby]

I've recently has the valve stem seals replaced. But I neglected to get the valve guides checked. Either way the head has to come off.

How does one correct worn valve guides?

Cheers
Shiru

 

[television]

when the head is off, take the valves out and the stems can be checked with a micrometer,those worn beyond the limit must be replaced, the same goes for the guides.

It is better to take the head to specialist who fits guides and laps the valves in.
Re bottom work, yes you can change the big end shells in sittu but not the main bearings, this is not a good idea as one worn bearing means the end of the oil presure.
When the head is off, if the bores are OK, I would leave alone the block if the oil presure was OK, as you start to go into big money.

Malcolm

 

[shirubaby]

yup oil pressure is fine. 3 bar at 3000rpm. and 1 bar at idle.

 

[television]

yup oil pressure is fine. 3 bar at 3000rpm. and 1 bar at idle.

Then just slip the head off and take it to a specialist.

One of the best is in Newcastle under lyme not that far from you.

Malcolm

 

[shirubaby]

Engine rebuilt!!

If it's worth doing you gotta do it yerself!

I had the 300ce coupe in my friend garage for nearly two weeks now on a slow engine rebuilt.

I can honestly say that i was amazed by the build quality of the engine. We took the head off and we could still see the original factory honing marks on the cylinder walls. This is on an engine that's done 115 000 miles.!!!!

There was a tiny ridge on the top that wasn't worth even getting rid of.

Anyhoo, we cleaned and cleaned and cleaned. Replaced piston rings and big-end bearing shells... and put everything back together (with new gaskets of course and new stretch bolts).

Started the car yesterday and she sounded great. Minimum smoke! So I've fixed the problem...whooo hoo!

With all the parts and tools I needed (e.g. ball splitter, specialist spline bits, hub puller, engine degreaser, engine assembly lube)..the total cost came to around 500 pounds. I will add a bit more to this in order to treat my mate to a nice indoneasian meal this week.:grin:

I also found the mechanic (who did the previous head work) fitted the valve stem seals the wrong way round (i.e. large aperture stem seal on the thinner valve stem and vise versa)...:x :evil: :evil: correct now.

No valve guide wear to notice.

The haynes manual was invaluable, although I do have a few additional points I would like to add to it.
I should blog what I've done. and include all the pictures I've taken in the process.

All in all I found the work very straight forward. Certain things were easy (e.g. taking the head off and putting it back). Certain things were hard (e.g. tightening head gasket bolts and and taking out/installing the sump.)

I'm currently in the process of running in the car. Fingers crossed.

 

[shirubaby]

few of the things you need if anyone is considering doing this as well.

- you need a garage...with a pit to work under the car OR axel stands and trolly jack.
- a way to raise the engine off it's two front mounts by by 3 to 4 cm.

- Ball joint splitter to take the steering arm/drag link off.
- Gear hub puller to take the steering arm off the steering box spline.
- Impact wrench - some of the nut and bolts will be hard to take off... unless of course your strong. For a weedy chap like me use an impact wrench.
- gasket scraper - halfords
- an assortment of 1/2" drive and 1/4" drive sockets
- an accurate torque wrench - halfords
- angle gauge - halfords
- valve spring compressor - halfords - if you want to replace valve stem seals...might as well... new valve seals will come with the head gasket kit.
- piston ring compressor - halfords
- vernier caliper

specialist bits for socket spanner:
- A large diameter alan hex drive bit to take the engine mount bolts off from under the car....Halfords
- Spline bit for the head bolts...Halfords...comes part of a set.

- New locking nuts for the steering arm bolts....OR thread lock if using the old nuts.
- Head bolts.
- Big-end bearing shells - complete set
- Head gasket kit
- Sump gasket
- Piston ring set

- Engine degreaser - jiser
- Engine assembly lube
- Hylomar - blue - gasket compound.
- wd40 - to stop things rusting.
- carb cleaner - to clean around head mating surface and valves

- dishwasher - to clean pistons in...note: they rust fast.
- wire wool to clean piston crowns.
- high pressure jet washer for washing the engine block once degreased.
- camera - take plenty of pictures - will help in the reassembly
- a tipex pen to mark metal parts and keep them in order
- £3 tesco jeans which will be ruined by the end of this
- collection of choice sware words

 

[C220GJS]

Glad to hear you got the job done, I suspected from what you said that you wouldn't need a rebore or new guides, I totally agree about the build quality of these engines , it's a pleasure to work on them so long as you have the right tools . Congratulations on a job well done !!!.
Geo.

 

[Jay Kilby]

tug the engine out and strip it down before purchasing parts. the blue smoke will defo be valve stem seal and possibly valve guides. strip the engine compleatly and get it cleaned thoroughly by specialists then you will be able to asses what to replace. also make sure you have all the tools required BEFORE you start somebody has already placed a good list.

good luck

 

[anyweb]

few of the things you need if anyone is considering doing this as well.

- you need a garage...with a pit to work under the car OR axel stands and trolly jack.
- a way to raise the engine off it's two front mounts by by 3 to 4 cm.

- Ball joint splitter to take the steering arm/drag link off.
- Gear hub puller to take the steering arm off the steering box spline.
- Impact wrench - some of the nut and bolts will be hard to take off... unless of course your strong. For a weedy chap like me use an impact wrench.
- gasket scraper - halfords
- an assortment of 1/2" drive and 1/4" drive sockets
- an accurate torque wrench - halfords
- angle gauge - halfords
- valve spring compressor - halfords - if you want to replace valve stem seals...might as well... new valve seals will come with the head gasket kit.
- piston ring compressor - halfords
- vernier caliper

specialist bits for socket spanner:
- A large diameter alan hex drive bit to take the engine mount bolts off from under the car....Halfords
- Spline bit for the head bolts...Halfords...comes part of a set.

- New locking nuts for the steering arm bolts....OR thread lock if using the old nuts.
- Head bolts.
- Big-end bearing shells - complete set
- Head gasket kit
- Sump gasket
- Piston ring set

- Engine degreaser - jiser
- Engine assembly lube
- Hylomar - blue - gasket compound.
- wd40 - to stop things rusting.
- carb cleaner - to clean around head mating surface and valves

- dishwasher - to clean pistons in...note: they rust fast.
- wire wool to clean piston crowns.
- high pressure jet washer for washing the engine block once degreased.
- camera - take plenty of pictures - will help in the reassembly
- a tipex pen to mark metal parts and keep them in order
- £3 tesco jeans which will be ruined by the end of this
- collection of choice sware words

id love to see your 'howto' instructions for this with photos,

please do post a link here if you get around to doing it

well done
cheers
anyweb

 

[clive williams]

If it's worth doing you gotta do it yerself!

.................
There was a tiny ridge on the top that wasn't worth even getting rid of.

....... Fingers crossed.

Shiru,

I don't want to burst your bubble BUT - that little ridge you quote should have been removed by a cylinder hone or a patented ridge buster. The ridge is made as a result of the wear produced by the top ring you took out. A new ring will probably due to production tolerences hit this ridge and quickly fail! I know I speak from experience. In the past when rebuilding engines was more common AP Hepolite used to make rebuild ring kits which were machined to take the ridge into account but these I understand are no longer available.
When checking the engine bores did you carry out the full checks ie
Bore ovality
Bore taper
Ring gaping
All of these should be done with a head plate on to simulate a torqued head but depending on the vehicle use may not be strictly necessary.

Clive

500E
E320CDIT210

 

[shirubaby]

we did re-hone the bores and they were within the specification given in the Haynes manual. The re-hone got some of the ridge out. I was only going with the advice given by my mate who's done a lot of engine rebuilding.

 

[television]

Congratulations, you seem to have taken care of all aspects, with new big end bearings, the throw of the con rod is going to be shorter, OK its only microns and I doubt if you will get any problem. Shame all of these engines are now so big and heavy, it used to be good fun having the engine on the bench. dismantling, laying under the car with the oil dripping on your face as you undo the big ends, then rotate the crank shaft to get the next one, more oil runs all over you. Nothing quite like the feeling of having done it yourself, it becomes personel.

Malcolm

 

[shirubaby]

So true Malcolm,

One of the main reasons I chose to do it myself (with help from handy Andy) was that I have now the same knowledge (if not more) my dad used to have when he took apart engines when he was a bored medical student.

It's the kind of mechanical confidence sadly lacking in most of my contemporaries, who will quite happily give it to the dealership to carry out repairs.

I have also graduated to 4 spanners according to Mr. Haynes :grin:

 

[shirubaby]

Uh ohh!!! Maybe I spoke too soon.

I've just been clearing out all the odd's and end's from my engine rebuild and came across the head bolt installation instructions, which we followed to the letter (or so we thought). The small print on the bottom corner of the page specified that the bolts need to be loosened 90 degrees and then re-torqued.

A small arrow symbol = loosened!!!! Groan.

Anyhoo the end result is that we've tightened the bolts more than necessary and by 90 degrees.

Is this bad? What should I do?

Shiru

 

[television]

Uh ohh!!! Maybe I spoke too soon.

I've just been clearing out all the odd's and end's from my engine rebuild and came across the head bolt installation instructions, which we followed to the letter (or so we thought). The small print on the bottom corner of the page specified that the bolts need to be loosened 90 degrees and then re-torqued.

A small arrow symbol = loosened!!!! Groan.

Anyhoo the end result is that we've tightened the bolts more than necessary and by 90 degrees.

Is this bad? What should I do?

Shiru

I do not think you will ever know the right answer, it was not so long ago that it was standard practice to tighten down finaly after 500 miles, I would just back them off, one at a time in the right order and re torque, then angle. you normally apply the angle after torque setting. Don't worry it will all be OK

Malcolm

 

[clive williams]

I do not think you will ever know the right answer, it was not so long ago that it was standard practice to tighten down finaly after 500 miles, I would just back them off, one at a time in the right order and re torque, then angle. you normally apply the angle after torque setting. Don't worry it will all be OK

Malcolm

Malcolm,

I don't think you can do that with stretch bolts, once set they have to be discarded if they are loosened as they have passed their plastic limit. In this case I would check the torque that the bolts have been tightened to and monitor them over a period of time to ensure they won't loosen. Alternatively, fit another set of bolts.

Clive

500E
E320CDIT210

 

[television]

Malcolm,

I don't think you can do that with stretch bolts, once set they have to be discarded if they are loosened as they have passed their plastic limit. In this case I would check the torque that the bolts have been tightened to and monitor them over a period of time to ensure they won't loosen. Alternatively, fit another set of bolts.

Clive

500E
E320CDIT210

Hello Clive, good point, though we had stretch bolts back in the 1920's they were only disgarded after they had reach a certain length, So heads these days are not pulled down after X miles. OK modern heads are torqued to a much higher level than back then. Maybe Shirobaby should just leave them as they are, what do you think. I don't quite get the bit then about loosening and then re torqued, as the angle is normally applied after.

Malcolm

Malcolm