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Cylinder head rebuild help!!! (with pics)



  '02 Monaco Blue 172
Some of you may or may not know that my car has been using a hell of a lot of oil ever since I had the engine rebuilt after an unfortunate cambelt failure about a year ago.

After asking a few questions on here, reading lots of old posts and the reading the f4r manual numerous times, doing a compression test and coming to the conclusion that the valve guides are probably leaking/cracked, I decided to have a go at stripping it myself to sort.

my plan is was to strip the head out, get it checked by a machine shop and get all valve guides replaced, new head gasket set blah blah blah.

Anywho, I got all the reno timing tools and any other tools that I needed, all spare parts before I started, and spent the best part of yesterday getting the head out, it all went to plan (except getting coolant everywhere), just took a bit longer than I expected. I then spent this morning stripping the head of valves etc.

I've taken loads of pics and am going to do a proper project thread when its all sorted but wanted to check a few things with these pics.

The top of the pistons have quite heavy build up of carbon, as in this pic



and the valves look in a pretty bad shape with carbon build up



the head is currently with a machine shop but I didn't want to rebuild it all if the piston rings are at fault. what are the tell tale signs of piston ring failure as opposed to leaking guides and what is the best way to get all this build up off?

the valve chambers looked like this when stripped



oh and when I stripped it, the only thing I forgot to do was drain the coolant and it went everywhere, i've got rid of most of it now but is it going to ruin everything?

cheers
 
  ibiza cupra
could it possibly be the timming that causes the build up of carbon. im just thinking that if the timming is out, then the valves may not open when they are suposed to and keep the exhuast gasses in the cylinders under pressure for longer than it should. im no expert but that would be what i thought.
or thinking about it, worn cams could have the same sort of effect.
stick it in a bath of petrol though mate, soon be nice and shiney lol.
 
  Focus, GSXR1000 & R6
Iv not seen a reno head but have seen plenty of bikes ones.
What sort of mileage have you done since it was rebuilt? I reckon enough miles would do that, are there some valves worse than others? As in where only some replaced when the cam belt went? Was the head even decarbed and cleaned up last time?

I cant see it being anything to do with piston rings, if they where that bad i would have thought there would be a lot of oil on top of the pistons?
 
  '02 Monaco Blue 172
Was rebuilt about 53,000 and is now just short of 60,000.
I was told that all valves were replaced but cant be certain! not really sure if it was decarbed last time as I didn't see it happen, this is the first time i've taken it apart myself but seeing other threads similar to this, most have much internals!

Reputable ren specialist garage did the repair originally so I think the timing should be right, but i said to it on as cheaply as poss as I was skint so thats prob why they never suggested doing the guides?
 
  Focus, GSXR1000 & R6
Hmmm would not have thought that much build up in that mileage but maybe?
Did they use second hand valves due to budget?

Like I said I don't know car engines but in my experience if a valve guide is gone then there are obviously cracked/broke!

If its using oil I would have said valve stem oil seals not guides?
 
  '02 Monaco Blue 172
just checked and it happened at 50000 miles, jul last year! and all valves were replaced!
 
  Focus, GSXR1000 & R6
If its burning oil it may just be the extra carbon, so I would guess valves stem seals, i would have thought you could see any damage of the guides.

Is it just in one cylinder or or all four the same?
 
  '02 Monaco Blue 172
all cylinders are fairly similar to be honest, just had a look at the valves and some of them look like they've been scratched when installed near the top of the stem which would ruin the seal I think! I might replace the valves too!
 
  RS CLIO 197
if its been burning oil thats the reason for the carbon build up on the pistons and valve faces

a lot of build up there - almost like the velves havent been replaced !

but looking at the valve seats they dont look to bad at all

if the guides are worn you will get excessive movement of the valve stem in the guides - also the valve guide seals sometimes go hard and crack and this can cause oil burning (early vauxhall cavalier engines example)

you will need to check the wear on the bores - piston fully down and then see how much of a ridge is near to the top of the bore - usually worse on the "thrust" side

but good work so far:star:
 
  172 Cup
sounds the easier option! how much? where are you based?

Down near cambridgeshire. Straight down the A1. I had mine rebuilt when i rebuilt the short motor (missus blew cyl 1 rings).

The head rework cost me over £400, i have the reciept to prove the work and date etc. It was over a year ago but has never been run. In the end i brought a 35k engine that appeared on here. I was not happy with my bores as they measured up oval and very close to the tolerance's.

Id happily take £300 collected or £340 posted mate.
 
  '02 Monaco Blue 172
I did notice a ridge about 5 mm around the top of the cylinder bore, you can see it on the left in pic 1. Is this ok?
 
  Focus, GSXR1000 & R6
There will be your normal carbon build up round the top of the bore, use scotchbrite or something and clean that off, then run your finger up the bore and see if it rises around the top
 
  172 Cup
I did notice a ridge about 5 mm around the top of the cylinder bore, you can see it on the left in pic 1. Is this ok?

This ridge is where the top compression ring doesn't quite reach the top of the cylinder.

At TDC does the piston move excessively? From what ive seen from the pics i would put it down to a cracked valve stem guide. They are made from bronze as standard and very weak. Any impact from the belt snap could have caused it.
 
Drain the coolant before you put the head back on so your 100% sure there is no water in the cylinders. No going back after hydrolock. :(
 
  Hyundai i30, Dog Van
this may have already been said but to check if ur piston rings are worn use ur hand to move the piston from side to side etc if thers alot of play then there fucked, (shouldnt be anymore than 1mm-1.5mm play) can be hard to tell though :)
 
  '02 Monaco Blue 172
I tried to move all of the pistons and they move very slightly, maybe around a mm, is this acceptable?

In the first pic, how can I get the coolant out from the holes surrounding the cylinders?
 
  '02 Monaco Blue 172
Just got a call from the machine shop and they said there is no damage to the valve guides, none are cracked and they are all within tolerance.

One thing I did notice when I stripped the head was that all the stem seals just slid off with no resistance, i've googled this and it says they should sort of clip into place, can anyone confirm this?
 
  Lionel Richie
yeah they don't just slide off easily requires some effort to get them off, i bet when it had a rebuild they weren't renewed

what did your compression test say?
 
  '02 Monaco Blue 172
cant remember what the readings were as I did it a while ago but all 4 cylinders were pretty low and all stem seals came off pretty easily, i'm guessing they weren't put back on properly.

I have a full headgasket set though for rebuild time so I know exactly what is going on. Also just bought a full set of valves as I thought that would be easier than scraping all that carbon off the existing ones!
 
  2005 Nissan Navara
Seen as the engine is in bits, the most sensible thing to do is just rebuild it, replace everything, and check everything is as it should be. Not much point in second guessing when its all apart anyway.

To check the rings, you need to remove the pistons. You simply cant tell if they are damaged with them still in the bores. Guessing at excessive movement at tdc isnt good enough, and certainly wont show up cracked rings. Remove the pistons, check the installed end gap, and feel the edges which sit against the bores...if they are sharp/shiney, then they are likely excessivley worn. If in doubt, replace them.

Same with the bores, you really cant determine a bores suitability by feel alone. You need to get a bore gauge, and measure the diameter through the full length accorss the thrust axis and at 90* to it. This will allow you to see any taper or O.O.R.
 
  '02 Monaco Blue 172
Cheers for advice everyone, made big progress today, lapped valves and rebuit head, looks like new again! Took most of day tho, especially to get spring retainer things on! One thing I couldn't figure out when stripping it, how/ where do u turn engine over by hand? Manual states releasing flywheel but couldn't work it out and need it to time up! I got it to tdc on strip by turning phase pulley with ratchet but had a lot o resistance and sure it's not the correct way to do it!
 
  2005 Nissan Navara
dont turn it over by the cam pulleys! get a socket on the crank pulley bolt.

what were the piston rings like?
 
  '02 Monaco Blue 172
Is the crank pulley bolt the bottom timing belt pulley bolt?

The pistons/rings seem good condition, hardly any movement and bores look good. I think/hope the oil usage is due to the stem seals. When I removed the old ones they just slid off, no resistance, when i fitted new ones today had to tap them on with a mallet and socket! Thinking they weren't renewed when it was rebuilt! Really hoping this is the problem.
 
  '02 Monaco Blue 172
Well I build it all back up today. Went to start it when everything was back in place and it started fine but it wouldn't rev. The revs are hanging at about 2000 rpm but there is nothing when I hit the accelerator, revs just stay constant. Everything else sounded ok. Had the orange centre ecu light on that is a jagged line and also the bottom right one on the right of the dials, cant remember what image it was!

Anyone any ideas what I need to check. It was raining when I put it back together, could the rain damaged anything?
 
Well I build it all back up today. Went to start it when everything was back in place and it started fine but it wouldn't rev. The revs are hanging at about 2000 rpm but there is nothing when I hit the accelerator, revs just stay constant. Everything else sounded ok. Had the orange centre ecu light on that is a jagged line and also the bottom right one on the right of the dials, cant remember what image it was!

Anyone any ideas what I need to check. It was raining when I put it back together, could the rain damaged anything?

I had this after doing a cam swap for someone, forgot to plug the throttle body back in......it idled at 2k
 
  '02 Monaco Blue 172
f0xy your suggestions was spot on, had a look around and could't see anything immediately but then spotted the plug under the throttle body, plugged it in and hey presto, it revved!

I do have a couple of other problems though. I seem to have developed a leak from somewhere, couldn't see anything straight away so going to have to have a closer inspection this week. not sure if it is oil or coolant, any ideas?

Also I still have a dash light on tho as below



any ideas what might have caused this to come on?
 
  '02 Monaco Blue 172
Yes it's on constant, where is lambda connected to engine?
Would a leak from exhaust manifold cause it?
 
  clio 182cup
underneath the car on the exaust you'll propablly see one lambda beofore and one after the cat.
Beside cat is a conector and then to ecu.

yes lambda sesor messure oxygen on gases, so if there is a leak before cat that maybe the problem.
 
  '02 Monaco Blue 172
Been out in the car this morning and the light has gone out which is great.

Still pi$$ing oil from somewhere though, I'm worried its from the cam pulley seals or dephaser as its on the drivers side. Wont have a chance to look at it till wednesday now! anyone any ideas after the work i've done?

I did renew all seals when rebuilding but worried i've not put one back on correctly, can you change the pulley seals without taking rocker cover off?
 
  ITB'd MK1
did you notice that the cam pulley seals are different on each cam? The inlet cam seal actually seals on the de-phaser and not the cam. If you fit the wrong seal on the inlet cam it will squash when the de-phaser pulley goes on, seen garages do that before and it PISSES out oil
 
One of my seals (Exhaust) got 'nicked' by the rocker cover when I was tightening it down, and as a result of that is pissed oil out of the side of the head...

Most probably the cause, weather it be exhaust or the dephaser/inlet seal as danny said if its a considerable amount
 
  ITB'd MK1
One of my seals (Exhaust) got 'nicked' by the rocker cover when I was tightening it down, and as a result of that is pissed oil out of the side of the head...

Most probably the cause, weather it be exhaust or the dephaser/inlet seal as danny said if its a considerable amount

oops, should always push the seal in after fitting the cover.
 
  '02 Monaco Blue 172
One of my seals (Exhaust) got 'nicked' by the rocker cover when I was tightening it down, and as a result of that is pissed oil out of the side of the head...

Most probably the cause, weather it be exhaust or the dephaser/inlet seal as danny said if its a considerable amount

That sounds like a likely cause, I has the seals on the cams when I fitted the rocker cover (I did have the correct one on correct cam) and the inlet did get caught at an angle as I started tightening it until I realised! F00k!

Is it rocker cover off again or as the inlet seal has a larger inner diameter than cam do you think i'll be able to get it out?
 


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