Timing chain too loose?

[Mr.G]

Hi Adrian,

Thanks for asking, Albrecht kindly came today and we had a very productive and educational "for me" day! Thank you once again Albrecht, so very grateful!

On removing the oil pan we discovered a broken washer and as we removed the timing cover a small bolt fell out . It's head had been rounded off really smoothly and Albrecht realised that the bolt must have made the groove in the head, we insered it into the groove and it fitted perfectly. Pics will follow soon but basically the bolt must have got stuck between the timing chain and the chain guide, as the chain moved round it was spinning this bolt round and smoothing it out.. The timing chain is very shiny too - which makes sense now. As to how the bolt got there in the first place is a mystery since all the bolts within the engine are present, and this bolt is too small to be an engine bolt. It could have fallen in when someone had the valve cover off or possibly the oil cap.

We removed the head and the valves look in good shape and so do the pistons and piston bores, so that's a huge relief .

From what looked like a complete rebuild looks as if I have been very lucky... How that bolt didnt get stuck in the lower pulley and jammed the timing chain is a bigger mystery to me then how it got there in the first place!

I've got quite a bit of work ahead of me now.. but looking forward to it!

 

[adrianfr]

That was lucky George could have been a disaster. Adrian

 

[grolls]

You lucky sod!!!!!!!

 

[Albrecht]

Come on George, get those pics up here. It will be interesting to hear the resulting comments.......

 

[Mr.G]

Oh kere goes... (Picture trail servers are playing up so if pics don't show try later).

This is the mark that sparked off this thread, it was an unexplained groove between the timing chain and the chain guide.

I previously thought that the mark could have been created by a loose timing chain that was hitting the side of the head, but many on here were uncertain due to the shape of the gouge.

On removing the timing cover a bolt fell out and we found a variety of other bits in the oil pan..

The bolt was the most interesting bit of all as the head was smoothed out and so were the threads.

Since it had fallen from the timing cover area we tried to see if it fitted into the groove in the head and it fitted perfectly:

This is a clearer picture of the the mark it made:

The oil pan contained other smaller nasties too:

Here is a picture of the pistons and the valves:

The engine didnt smoke and it didnt burn oil and a compression test revealed all cylinders were withing specs.

Here's the bottom end:

On speaking with Mike yesterday he advised I removed the main bearing caps and the rod bearing caps and check them for scratches and wear.. I was hoping not to have to get so deep into this but it looks like Pandoras box is now open .

 

[Mr.G]

Can i just thoroughly clean oil pan and strainer and flush the head's oil gulleys with diesel or brake cleaner and then check the bearings and if the bearings are ok then just bolt everything back together with new gaskets or do i do a need to go the whole hog of a complete teardown including hot tanking the block?

Advice and suggestions appreciated..

 

[Russ]

Wahey get stuck in

So lucky that you didn't end up with a minced head! If we ever are over that way we'll lump the guy who built you engine, I can't think where that bolts goes so must have been a bonus one he gave you.

 

[Albrecht]

On speaking with Mike yesterday he advised I removed the main bearing caps and the rod bearing caps and check them for scratches and wear..

Are you sure he doesn't just want to sell you a set of bearings, George?

To be honest, the crap in the sump looks a lot worse in the photo than it did in real life. Most of it was soft and sludgy, and don't forget that an awful lot of junk from the sump gasket joint ( which was absolutely covered in horrible slicone sealer ) fell into the sump when we took it off.......

I was pleasantly surprised that the crankcase looked nice and clean inside, and the underside of the pistons looked clean and fresh too. No gummy deposits to be seen - which I think is good evidence of fairly frequent oil changes. Same for the head in the valvetrain area and the cam. No evident wear.

If it was my engine I'd completely strip it, but then I've done it countless times and I have the tools and know-how. Your situation George is slightly different, and I wonder whether you really want to start pulling bearings out? You can only ( reasonably ) check half of them without pulling out the crank anyway....

The ball is in your court now.

 

[Albrecht]

If we ever are over that way we'll lump the guy who built you engine.......

There's a queue forming:

http://www.zcar.com/forums/read.php?f=4&i=265625&t=265625

 

[datsun dave]

What a S**t mate what can i say go with the count you have to strip it all down as you do not know what other joys are there, if you just put it back in it will always be on your mind.

 

[grolls]

You lucky,lucky,lucky person

 

[Mr.G]

You lucky,lucky,lucky person

Well yes that is the best way of viewing it I guess, it could have been a lot worse if that bolt or washers got under the chain.

If we ever are over that way we'll lump the guy who built you engine,

Cheers Russ

if you just put it back in it will always be on your mind.

That is very true Dave.

The ball is in your court now.

Count as you know I would like to do it properly but it all looks very daunting at the moment! I am going to do what we suggested and then reasses and have another read of how to rebuild your datsun engine by Tom Monroe..

I just called a local company to find out if they do hot tanking and they said they can put it in a dishwasher type machine with degreaser, is this hot tanking? They only wanted £10.. seemed a bit cheap.. They were called Middlesex Reboring Company Ltd. based in Mill Hill, London anyone used them? Can anyone recommend a place or can anyone do a hot tank -- should I decide to go the whole hog that is.

Can someone give me a rough idea as to how much I am looking at spending to completely rebuild my engine.

Count - can you see me needing any more machine work other then a hot tank?

Thanks all.

 

[datsun dave]

MrG240z i know now as you say looks daunting but your engines out ,heads off 1/5 of the works done get it all striped down check it all over to see that the rests fine, have your block hot tanked and start a fresh YOU KNOW WHAT YOUR WORKING WITH and can buy new to replace worn/broken parts and build it up again.Best of luck with it all and i hope you get it all sorted ASAP

 

[Russ]

George: find me online later tonight and I'll run down what I think mine is going to cost.

 

[Albrecht]

Count as you know I would like to do it properly but it all looks very daunting at the moment! I am going to do what we suggested and then reasses and have another read of how to rebuild your datsun engine by Tom Monroe..

Good plan, George. No need to rush in blindly just yet.

They were called Middlesex Reboring Company Ltd. based in Mill Hill, London anyone used them?

Yes, I know them and they are OK - but I'd say that they are run-of-the-mill ( Hill! ) type of outfit. I wouldn't give them any machining to do - put it that way. Hot tanking etc - no problem.

But if you completely strip the engine down to the bare block you might as well have the crank cleaned and polished, rods resized, pistons cleaned ( or new pistons.....and/or new rings, etc etc etc ). Where does it all stop?

Your initial relief at the ( apparent ) good condition of your short block and head assemblies - and the hope that you could simply clean up a little and re-assemble - now seems to have changed to angst about how far to go. And everybody you talk to ( not forgetting that none of them have seen it ) will give you a different opinion.

I myself was mindful of the fact that you appeared apprehensive and were worried about expense and lack of tools / equipment / reliable contacts, and that is why I suggested that you might like to simply clean it all up and put it back together with a proper Nissan head gasket and a set of ARP head studs ( seeing as it had the wrong head bolts in it anyway ).

I know you are already 'window shopping' for higher-performance components, so I want to urge you to think about your ultimate objective, and whether or not you can afford or indeed need to go the whole hog.

And no, I can't see you needing any more machine work if you put back together what you already have. In fact if you were prepared to get a little dirty, and bought yourself some 'gun-drill' brushes and a job-lot of 'Jizer', you wouldn't even need to get it hot tanked.

My initial recommendation still stands: Clean it all up, paint the block, re-assemble with all new gaskets and a set of ARP head studs, and you will be good to go. The only thing I'm actually worried about is that turbo oil-feed line ( I'd replace it ) and the bearings in the turbo ( get it checked and/or replace it ).



My offer of a helping-hand still stands........

 

[Russ]

Count: What is rod resizing? Is it making sure the big and small ends are correctly spaced or?

 

[Albrecht]

Pounding out the rod bearings badly enough can make the rods lose shape. They can actually become slightly oval, which means that the new rod bearings can be a bad fit ( to put it mildly ).

Re-sizing the rods usually involves taking a small lick off the mating surfaces of the rod and its cap, and then honing the rod with the cap on and the rod bolts torqued to spec.

If they are too far gone they are junk though.

I'm sure George's are fine, but if he was to strip the engine completely it would be worth measuring them properly.........

 

[Mr.G]

Count,

Thank you for the offer, I will really need it, especially when installing the timing chain!

I am going to stick to the original plan! You summed it up very well and you were spot on in how you put it. This is the soundest decision for me after weighing everything up.

If it spins a bearing then it's a chance I am prepared to take, I will rebuild it then once I have no other choice..

Thanks also to all with advice and encouragement of rebuilding, as much as Id like too I dont feel I'm 100% ready for this and hence the hesitation and inability to make my mind up, until now!

Really looking forward to getting cracking on it at the weekend ! I've taken Monday off too, that's Zedication!