TorontoTim Posted June 4, 2016 Report Share Posted June 4, 2016 Dear Sages, Recently, I've had symptoms of head gasket failure - specifically, steam from the exhaust pipe. Both inspection of the spark plugs (one clean/washed plug) and a compression test indicated that #4 cylinder was at fault. I've just removed the cylinder head, and I don't like what I see... There appear to be 1 or 2 cracks around the stud at the right rear of the block (see photos). Anyone able to definitively tell me whether this is terminal/fatal, repairable or nothing in the least to worry about (I prefer the latter)? Thanks, Concerned of Toronto. Quote Link to post Share on other sites
SuzanneH Posted June 4, 2016 Report Share Posted June 4, 2016 HI Tim, The cracks in themselves didn't cause the blown gasket ...but. What caused the cracks. It could be simple stresses from the torquing down. How deep are the cracks. Is it possible to clean the stud hole and water way to see if there is any depth ...I would have thought not. The stud may have pulled up causing the stress and relaxing the torque. If it was me I would ignore it apply some RTV between the gasket on the black around the stud and refit the head. Recheck the torque on that stud regularly to see if anything is moving. If things appear to be moving then drastic action may be needed. Roger Quote Link to post Share on other sites
Guest Posted June 4, 2016 Report Share Posted June 4, 2016 These cracks can be stitch welded. Google finds a few addresses in the Toronto area when you look for 'welding engine block toronto' Menno Quote Link to post Share on other sites
Motorsport Mickey Posted June 4, 2016 Report Share Posted June 4, 2016 Yawn...uh what terminal ?...nah. As long as there are no cracks in the cylinder liner and the figure of 8 liners are sealing and there are no cracks in the cylinder head then the minute cracks in the rear and front of the blocks are easily sorted with a proprietary sealer. I have as a Triumph Stag owner ( and many other Stag owners) have a closer than nodding acquaintance with K Seal. Because of the vagarities of the inlet manifold in the V of the Stag and various badly warped alloy inlets etc water leaks into the v of the engine are commonplace and using K Seal helps sort them out. To all TR owners now crossing themselves and looking for stakes and mallets a water jacket sealer is commonly used by myself when building race engines and never complained about in use ( that would be by me then lol). Most objections hinge around the possibility of blocking heater and radiator vanes ( NOT what you want on a Stag) but the K Seal actually states on the bottle that large aperture leaks are NOT it's forte. The extremely small copper and other particles suspended in the mix are best used to seal minute cracks or gasket sealing problems, hence why it should be eminently suitable for your hairline cracks into the studs. Of more concern to me is the liner heights on your engine. Make sure the liners are retained by washers with tubes and nuts torqued down to 40 lb ft ( or thereabouts, not critical) to prevent disturbing the FO8 seal. Carry out a measuring excercise with a depth micrometer at 4 points around their circumference from liner to block and ensure that they are all an even protrusion down the length, commonly you'll find that number 4 has less height than the others ( check out the search facility for liner heights, my fingers have blisters from stating how to do it). Then report back to discuss on how to sort it. Mick Richards Quote Link to post Share on other sites
Geko Posted June 4, 2016 Report Share Posted June 4, 2016 (edited) I would say that the cracks are unrelated to the blown gasket. Looking at the combustion chamber cyl 4, the coke seems to have been washed away on the other side, that is next to cyl 3. Mind posting a picture showing the head gasket between cyl 3 and 4 - both sides? Concern is the passage framed in red on the picture. Looking at the embossed gasket, protrusion seems to be doing its job but I would check if it's not too little as compared to the other liners.... Edited June 4, 2016 by Geko Quote Link to post Share on other sites
Stevecross Posted June 4, 2016 Report Share Posted June 4, 2016 If you are really bothered about the block a poster/member here (Dalbuie) Has a block for sale. He put a presale of his stuff up on the tr2/tr3 Forums but now up for grabs on ebay. Bought a couple of items from him. an honest & excellent person to deal with. Steve Quote Link to post Share on other sites
TorontoTim Posted June 4, 2016 Author Report Share Posted June 4, 2016 You guys are making me feel hopeful... Here's a bit more of the gasket... Quote Link to post Share on other sites
Geko Posted June 4, 2016 Report Share Posted June 4, 2016 I'd think that the liner protrusion is too low there Quote Link to post Share on other sites
TorontoTim Posted June 4, 2016 Author Report Share Posted June 4, 2016 Ok - to start with, I'll check liner heights and report back. I'm slightly surprised, because the engine was a pro-build (not me) and it's been 10,000 miles since I replaced the head gasket on a rally just under two years ago. But I shouldn't assume anything, I know. The good news is that no-one has said it's scrap...yet... Quote Link to post Share on other sites
Guest ntc Posted June 4, 2016 Report Share Posted June 4, 2016 I will be the first Its dead. Quote Link to post Share on other sites
Rob Salisbury Posted June 4, 2016 Report Share Posted June 4, 2016 So long as you are not planning to go track racing with it then carefully mask off the whole area, drill the block deeper with the correct size for tapping a thread, tap the thread as deep as you can, counter bore the top 5mm or so and stick in a longer stud with plenty of RTV as suggested by Roger. My block has been repaired like that for years with no ill effects, I'd say it's sick but not dead yet, for road use anyway. Cheers Rob Quote Link to post Share on other sites
Motorsport Mickey Posted June 4, 2016 Report Share Posted June 4, 2016 Confused now. If the head gasket came off the engine in that orientation ie with the folded edges to the liners on the top it would be regarded as being fitted upside down, normally smooth side of gasket is to be fitted facing the head surface. The stud hole on the block showing with the cracks is the rearmost drivers side stud, and the photo of the head gasket in that set of 4 is the stud hole on the drivers side rear with the folded edges pointing down, the correct way. But the picture on post 7 shows the head gasket with signs of failure between liners 4 and 3 if fitted with these folded edges upwards or 1 and 2 if fitted with the folded edges fitted downwards. Given that the we think the blow is between 3 and 4 ( also as indicated by compression test) it shows that the head gasket was fitted upside down...I think, also If so look for a difference in liner heights between liners 3 and 4. Mick Richards Quote Link to post Share on other sites
TorontoTim Posted June 5, 2016 Author Report Share Posted June 5, 2016 I'm sorry, Mick - you're quite right. I took a photo of the wrong end of the gasket in post #7. Folded edges were down; smooth side was up (against the head). THIS time you should see the underside of the gasket (i.e. the face that was against the liners) for nos. 3&4... Quote Link to post Share on other sites
Motorsport Mickey Posted June 5, 2016 Report Share Posted June 5, 2016 That's a relief, 'twas making me head hurt". The photo is interesting but not conclusive, check the liner heights so we may confirm the basics are correct for liner clamp upon the gasket, all of them mind and around each liner in 4 orientations. Mick Richards Quote Link to post Share on other sites
TorontoTim Posted June 5, 2016 Author Report Share Posted June 5, 2016 Ok, I have measured liner heights (with straight-edge and feeler gauges) in 4 places each and have found that in MOST places, the height is less that .003". In fact, in a couple of places my measurements make it less than .002" The only places that I DO have .003" is on the pushrod-side of #4. First, does this tie in with how the head gasket looks (as far as you can tell)? Second, as I've done ~10k reasonably hard miles since the rebuild, does this sound right? Third, is it likely that they have receded (head has been off twice in this time) or is it more likely that it was built this way? Given all of the above, I am assuming that it's time for new Fo8 gaskets, yes? Quote Link to post Share on other sites
Don H. Posted June 5, 2016 Report Share Posted June 5, 2016 Tim, there are some folks here in NA that recommend a "fire ring" mod to a head gasket to improve sealing. The basic idea is to solder rings of dead soft annealed 0.018-in copper wire to the block side of the head gasket which improves sealing around the liners. Send me a pm if you'd like contact details for one of the guys who's pretty knowledgeable in this. Quote Link to post Share on other sites
Motorsport Mickey Posted June 5, 2016 Report Share Posted June 5, 2016 (edited) Hi Tim, Not unexpected, the range of liner heights in the workshop manuals is given as between 3-5 thou but that means as a set as in 4.4.4.4. Where you have an inside liner with a low reading ie 4.4.3.4. the outside liner acts as an escarpment and prevents the head deforming to increase the gasket clamp ( the heads about 3" thick and over a 4" distance between liners won't deform) and can often cause a weak spot on the gasket seal and a blow. This what's caused the discoloured area between 3 and 4 on the gasket as it failed. The FO8 gaskets don't pull down buqqer all so the liner heights you've got are likely what it started with. Twisting or tilting of the liner is another story. If the No 1 or No 4 liner is measuring low, because it doesn't have a supporting liner outside them there is nothing to stop the 105 lb ft torque on the outside short studs deforming the head a couple of thou and increasing the gasket clamp pressure on those outside liners so helping prevent a gasket blow, sometimes for a considerable time. Check the cylinder head for straightness and warping ( straight edge and feelers again), clamp the liners in position (large washers and tubes on the head studs ) where the liners siamese OO OO.. ...like this. Drop sump, unbolt big ends on all rods, push Pistons out and remove rods, cover the crank and oil pump gauze with cling film ( sandwich plastic film) to prevent dirt ingress and mark the liners for position ie 1.2.3.4. and orientation (drivers side). Wipe the top of the liners with thinners and write in indelible pen what you think the heights are now, then pull all 4 liners using a threaded rod with bridge piece suspended between a couple of the head studs to give you a couple of inches or more vertical movement. The bottom end will need a round diameter alloy plug turning to sit just inside the liner bore with it's outside dia being small enough to travel within the bottom spigot dia of the liner holes, make sure the plug is thick enough to withstand considerable force being applied through it, mine is 3/4" thick. Measure your existing FO8 gaskets for thickness after cleaning with thinners, there should be Wellseal or other non setting gasket goo material around them, then buy some copper FO8 gaskets at least 5 thou thicker than your originals. Spend an hour cleaning all c r a p and crud from off the liner shoulders on top of the spigots where these FO8 seals will go, (this is why you covered the crank) make sure there are no burrs or lifted edges around these FO8 copper gaskets where they've been stamped out by "stoning" flat, then refit the new FO8 gaskets DRY without Wellseal then refit the liners (you've got to clean the goo and c r a p off these too) in their correct positions and orientation and pull the liners down into the block by fitting your head and using the old head gasket, which you've cleaned any c r a p off, and torque down to 105lb ft. (Sorry Neil, Tim won't have a setting block, he'll manage fine using the head). Then remove the head and old gasket and fit retaining washers onto the head studs over the liners where they Siamese together on the inside and torque the liners down to 40lb ft (not critical) to prevent movement. Then remeasure the liner protrusions and report back, see how insignificant a hairline crack into a stud hole now seems ? lol all things are relative. Mick Richards Edited April 28, 2021 by Motorsport Mickey Quote Link to post Share on other sites
TorontoTim Posted June 5, 2016 Author Report Share Posted June 5, 2016 Blimey! Thanks, Mick. The only other thing I'll do first, is check how good my straight-edge/feelers measuring is by getting hold of a depth micrometer. Assuming no significant discrepancy with what I've measured so far, I'll work through the above and report back... FWIW, I cleaned out the thread of that rear stud and had a good look for evidence of the cracks being deep (as per Roger masquerading as Sue, above); there's nothing to suggest they are significant... Quote Link to post Share on other sites
Graham Posted June 6, 2016 Report Share Posted June 6, 2016 Blimey! Thanks, Mick. The only other thing I'll do first, is check how good my straight-edge/feelers measuring is by getting hold of a depth micrometer. Assuming no significant discrepancy with what I've measured so far, I'll work through the above and report back... FWIW, I cleaned out the thread of that rear stud and had a good look for evidence of the cracks being deep (as per Roger masquerading as Sue, above); there's nothing to suggest they are significant... Roger is only 'Sue' on weekends and holidays ATB Graham Quote Link to post Share on other sites
TorontoTim Posted June 9, 2016 Author Report Share Posted June 9, 2016 Ordering parts today (have been delayed by iffy weather as I'm working outside)... Quote Link to post Share on other sites
RogerH Posted June 9, 2016 Report Share Posted June 9, 2016 (edited) Hi Tim, nothing wrong in using feeler gauges. However straight edges can be troublesome. I use a 1/2" diameter length of silver steel - it comes ground to size and is straight. Being round you can't tilt it and create a false gap. Roger (Grayson Perry eat your heart out) Edited June 9, 2016 by RogerH Quote Link to post Share on other sites
TorontoTim Posted June 15, 2016 Author Report Share Posted June 15, 2016 Quick update: I have everything apart; have spent well over an hour cleaning both the liner seats and the liners themselves; have ordered some new (and very shiny) copper Fo8 gaskets (thicker than the previous ones) and bought what I think is a good substitute for Wellseal, which I can't get here. (I chose Permatex Aviation #3: https://www.permatex.com/products/gasketing/permatex-aviation-form-a-gasket-no-3-sealant-liquid/which is brown and gooey...sound ok?). I also have a spanky new head gasket from Racetorations and new big-end bearings (County, tri-metal). While I was there, I ordered a new .75" brake master cylinder which was bloody expensive!!! Tomorrow I have a few too many things going on, so may not get a chance to dry fit the new Fo8's. So, on Thursday I hope to report back on the 4 measurements for each of the 4 liners... Roger - I'm still on the straight-edge and feelers; mine is a short length of box steel which I have checked against about many things to ensure straightness... Quote Link to post Share on other sites
Graham Harris Posted June 15, 2016 Report Share Posted June 15, 2016 Permatex aviation is much the same as Wellseal, i have used it for years and my old Dad used it as well. You will need paint thinners or similar to get it off your fingers or any spillage it sticks like the proverbial to a blanket; Graham Quote Link to post Share on other sites
TorontoTim Posted June 15, 2016 Author Report Share Posted June 15, 2016 Thanks, Graham. Good to know. Quote Link to post Share on other sites
TorontoTim Posted June 18, 2016 Author Report Share Posted June 18, 2016 (edited) Dry fit and initial measurements taken. (I will re-measure tomorrow, pending any comments here). Results are (in thousandths of an inch): Cyl: NW: NE: SW: SE: #1 6 6 6 6 #2 6 6 6 6 #3 5 5 6 6 #4 6 6 6 6 FYI: compass points as seen from the pushrod side of the engine. All nice and uniform EXCEPT for the non-pushrod side of cylinder #3, albeit at .006" which is higher than spec. Thoughts? Edited June 18, 2016 by TorontoTim Quote Link to post Share on other sites
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