Jump to content

Cylinder head, Cracked?


Recommended Posts

Hi 

The engine on my TR4 restoration project was seized, so I don't know whether it was a good runner when it was laid up circa 30 years ago. It is all in bits now and I'm starting to look at the head.  It' a 511695 and after cleaning it up, I noticed what appears to be a crack between the inlet and exhaust ports on number 1 cylinder. I guess this means my hope to just lap in the valves, is over. 

It looks to me as thought the Exhaust valve seats already have an insert fitted, would getting new seat for the inlets, fix the problem.

IMG_1414.thumb.JPG.b4efd89140e92d2f1a1bb69486e280c5.JPG

Thanks

Paul

 

Link to post
Share on other sites

Hi Paul,

it must be worth a try.

Ask the machine shop that if a small crack remains after machining  could the remnant of the crack be brazed etc simply to hold it together

Certainly worth asking.

 

Roger

Link to post
Share on other sites

Might be work a call to Cast Iron Welding Services and ask them. The inlet valve seat is goosed too and even a seat (I guess they are available somewhere) you would run the risk of it dropping.

Link to post
Share on other sites

I can't help wondering if the crack is the result of fitting the hard exhaust seat ?

Bob.

Link to post
Share on other sites

Might be worth asking Hamlin  Tel: + 44 (0) 1278 422452 what they would do, they now get cracked blocks Laser welded with good results. They have a lot of TR knowledge.

Iain

Link to post
Share on other sites
1 hour ago, DaveN said:

Might be work a call to Cast Iron Welding Services and ask them. The inlet valve seat is goosed too and even a seat (I guess they are available somewhere) you would run the risk of it dropping.

Only seat fitted on the exhaust valve Dave, not normally needed on the Inlet (fuel charge cools it more).

Mick Richards

Link to post
Share on other sites
  • 1 month later...

A bit of an update, but more advice needed:

I had the head tested, but surprisingly it only needed a new core plug and 5 thou skimming of face.

I've got the engine back in the car, but I'm not ready to run it yet (waiting on a exhaust and some fuel line), but being a little be curious, I decided to do a compression test.

I'm a little disappointed with the results, No.1=3=4 at about 120psi, but No 2 is only getting approx 80psi. The crack was on No.1 so that is not an explanation.

The question is whether this can be expected on a newly rebuilt engine and I should continue on to see what happens, or should take it apart again to find out what is wrong with No.2?

 

Thanks

Paul

Link to post
Share on other sites

Hi Paul,

the pistons, rings, and valves  need bedding in. Give it 500 - 1000 miles and then test again.

Did the workshop do anything with the crack. I would be surprised if they didn't - most odd.

 

Roger

Link to post
Share on other sites

“The question is whether this can be expected on a newly rebuilt engine “

OK...give us a clue, from what you say this “ newly rebuilt engine” is the original engine block and bottom end but just has the head refitted with a new head gasket ( what sort) and with a new core plug and a 5 thou skim...is that correct ?

If it’s had work carried out on the block and bottom end ( pistons,rings, honed liners etc) or on the valves and valve seats, what was it, and were the engine liner heights checked before the head was refitted, and have the tappers been reset ? All this info is necessary to decide what may be wrong, and searching this thread I can’t see where it’s been given.

MickRichards

Link to post
Share on other sites

Hi Mick

Its had a complete strip and rebuild, one of the big-ends was rusted. Most parts are new but I have reused the liners (no wear ridge, just honed them) and pistons but with new rings. Pistons were +030 so I assumed they have been changed relatively recently. I also reused the valves (cleaned and reground). When the head came back, I did a quick check to see if the valves were leaking, filling the combustion chambers with petrol and all seems OK.

I read the many guides about the liner heights, so I went through the pain. I had to use steel fo8 gaskets to get acceptable protrusions of 3 to 4 thou. The valve clearances have been set, and as its easy, I have double checked to see if anything was amiss on No.2, but clearance still looks OK.

Hope that helps with a bit of the background.

Cheers

Paul

 

 

 

Link to post
Share on other sites

Hi Paul,

if you are happy to have a small gamble on the head surviving for a decent time then go for it.  But be prepared for a head removal at sometime in the future..
 

The head is easy to remove when necessary - BUT if the crack grows it will probably take the head gasket with it and this then may require the block to be reskimmed.

AND at present the head crack is repairable for £100 or so.

If the crack grows it may become un-repairable. A second hand head of unknown quality will be  £400 +++

A new head will be £2000+++

Confirm with the workshop as to what they did with the crack. If they did nothing then remove it and get it sorted - it will save you ££££££££££££££££££££

 

Roger

Link to post
Share on other sites

That RogerH is always on the money, if using the car for 3000 miles a year the crack may not immediately be a cause of a problem but is it the sort of potential failure you’d be wary of, if going for a 3000 mile across continent trip.
As Roger says because of the rehone and inner engine work it’s difficult to precisely pin the extra lower compression on the No2 cylinder, his good advice is the way to go, 1000 miles (including the necessary head retorque) and then retest the compressions. With such a drop on the No2 cylinder it’s possible there’s a ring problem but it’s either strip now or bed the liners in to get compressions but risk damaging that low compression liner if a ring is broken.

Mick Richards

Link to post
Share on other sites
1 hour ago, gloide69 said:

Well, it didn't take too long to get No.2 out to check, glad I did.

IMG_1491.JPG

Well done, a small pain now prevents later shenanigans out of all proportion to what it’s just cost you. 

Mick Richards

Edited by Motorsport Mickey
Link to post
Share on other sites
  • 3 weeks later...

To be fair it is not unheard of to bust a ring on assembly but you usually hear that sickening noise as you do it so carrying on having heard it is frustrating as it means much more work that if you do it at the time!

Who rebuilt your engine? Rusty bearings is a worrying sign of a job done badly.

At least you have go to the bottom of the issue.

Link to post
Share on other sites

What did they do to sort the head crack? Putting an insert into the inlet should machine away most of the crack and the two inserts then sandwich a crack which goes to nowhere providing the machine shop is good and has the right inserts

Link to post
Share on other sites
3 hours ago, Andy Moltu said:

 

Who rebuilt your engine? Rusty bearings is a worrying sign of a job done badly.

 

I understood that was one of the reasons for the rebuild.

Pete

Link to post
Share on other sites
15 hours ago, Andy Moltu said:

 

Who rebuilt your engine? Rusty bearings is a worrying sign of a job done badly.

 

Read the OP Engine hasnt been run in 30 yrs and then rebuilt due to rust.

Stuart.

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.