My donor is a sierra with a CVH 1800, it has had a timing belt failure and the previous owner was unable to get it running again, I had a look and he had fitted the new timing belt but hadn't aligned the Cam and crank sprockets. After aligning them I was able to get the engine started but just barely, it wouldn't rev past maybe 1000 rpm, wouldn't idle and was very lumpy. I have since had the head off and was thinking I would find clear damage to the valves but now that I look at it there is no apparent damage. I should have done a compression test while the head was on but now that is it off what would I expect to see if the valves were damaged. Do they break or just bend? The valves themselves have little clean areas where it appears they have at least touched the piston but they don't appear to be damaged. Also how do I go about getting this thing cleaned up?

Advice?

here are some pictures

CVH engine are normally quite good, when the cam belt goes the engine dies and oil pump stops.. the causes the hydrolic lifters to loose pressure and the valves close.

if the valves had hit the pistons it would have net them, take the valves out and and check the seats, regrind the seats as well, you will see if the valve meets all the way round the seat... or tip some fluid in the head when it's upside down to see if the valves leak.

also can you see any marks on the tops of the pistons ????

Not quite the same but when I over revved my CVH one of the inlet valves touched a piston and bent just enough to not seat properly - needed a new valve and guide. I had a clean area on valve just like yours.

There aren't really any marks on the pistons, They have little reliefs in them where the valves sit but there are no marks in them though some are cleaner than others, the pistons sure are dirty too, covered in deposits of some kind. Carbon?

The mark you can see on piston one is from my fingernail.

The marked valves will almost certainly be bent, but a compression test would have told you this before you stripped it!

I have a 1.8cvh engine spare now as i've changed it for a zetec + carbs. The only thing wrong with the engine is the crank needs regrinding but the head and valves are in very good condition with new valve lifters.

The engine ran very smooth with the only problem being a knocking big end. Wasn't worth a regrind and everything else so changed engine.

I'm up in the North East so you're welcome to it if you can collect it.

Cheers....Andy

Any Idea how much a complete new set of valves run? Do I need new lifters and springs also? Does anyone sell a complete kit of some kind. Would I be better off finding a second hand head somewhere?

Cost is a factor at this point I just want the engine running and am not worried about increasing performance unless it can be done for similar costs as replacing with standard parts that I need to replace anyway, I might consider trying to mildly port the head myself to clean it up slightly and to match the manifolds. I want to get the car through the IVA with this engine for age related plates and for the emissions.

Wow Spud, that is a generous offer but I don't really have any way to collect it. Where are you exactly (duh, just had a look at your profile), I may be able to borrow a small trailer to collect it in if its not too far but I suspect it might cost me more to collect it than to get a head from the scrappy.

[Edited on 17/3/2009 by Keith Weiland]

The marked valves will be bent but to check, take the rockers off so the valves are all closed and then pour some petrol in the inlet and exhaust ports, one at a time. Any bent valves will let the fuel seep/run past.

Take the suspect ones out and check (roll them along the edge of a table, look for wobble in the head).

So can I just change the bent ones? any advice on cleaing it up, can I just use parafin and a brush? is there a better way?

use oven cleaner to remove carbon deposits.

Ive just done an ohc corsa engie withe similar damage. Valves are so weak that any marks will indicate that they are bent.

Not sure on the guide material, the corsa had bronze ones and ther was no sign of damage to I risked reusing them and got valves on ebay £40 for the set)

If its on steel or whatever guides they may be cracked and will seep oil.

to test them in situ as suggested, ensure they are all resting on the seats, and fill the chamber with paraffin, petrol evaporates, parafin/diesel wont.

Keith, as adithorp suggests the way to check if they are bent is to roll them around on a flat surface, but there may be some that are ever so slightly bent & it may be hard to decide one way or another.
I was a technician @ a Ford dealer for 25 yrs, I have repaired many of these and the only damage I encountered was bent valves, don`t recall anything more serious. Your pistons look as though the valves have touched them, hence the shiny half moon marks, but it won`t have hurt them, for peace of mind I would fit a full set of 8 valves & be done with it, this will pretty much guarantee a good repair, by the way if you have to hit the valves to get them out of the guide, they are bent!
Dennis.

A CVH will always bend valves if the belt breaks ----


It is also possible you will also find valve guide damage.

A good way to test for slightly bent valves is to put the head on its side and fill the ports to the top with kerosene, if the valves are in a really bad way it will leak out very quickly. If not you can do a more severe test if you then direct a jet of compressed air round the edges the valves working right around the circumfrence --- if you get bubbles in the port the valve isn't sealing.
Do both inlet and exhaust ports this way.



[Edited on 17/3/09 by britishtrident]

To clean it all up, once it is dismantled get a large plastic box ( storage box type thing) 1/2 gallon of parrafin and some cheap paint brushes and an old tooth brush scotchbrite pads are good as well. Once it has all had a good clean with that and rinsed dry it all and then spray it with either cilit bang or if you have a home bargains neaar you their own version is called Bam and its just as good and only 89p. more scotchbrite keep repeating and rinse with warm water and blow it all clean with an airline. Mine took 3 hours to do you can see the results in my photo archive. If you have a lathe or drill you can mount the valve in the chuck and carefully scrape and grind the crap away, then re-lap the valves in.
Kev

A CVH will always bend valves if the belt breaks ----



Rubbish !!!! i have broken a timing belt in my XR2 twice and it never bent the valves

how the bleep did you break 2 belts?

Thank for all the advice,
I think I will just fit 8 new as drury suggests and be done with it. Otherwise if anyone near hinckley had a good CVH head they done need

According to Google map you're only 173miles away, you could collect it for £30. Cheaper than a set of new valves and all the rest....

Only if it would fit into the boot of an Audi a6. .

itll go in a corsa!

I suppose technically it would fit in the Audi but only sideways with oil running everywhere.

plastic sheet in the boot, drain the oil before you put it in and lie it down with the head propped up on something then tie it in.

Fitting wouldnt be an issue.
- But as said, it all depending how posh the A6 is and how confident you are in your plastic sheet!


Daniel

To be honest the bottom end is no good but the head is in excellent condition, could soon take off the head and put it in a box. There's also a nice K&N bolt on chrome filter to go on the Pierburg.

Be a shame to throw out all the old bits when it could go to a good home. Misses is starting to complain now...

If you are ok with me just coming up with my tools and taking the head I think I could manage that. The question would be when I could come up? I reckon it would take me 3 hours up and 3 hours back plus a bit of time to take off the head so a full day for me

Sent a u2u Keith..