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stewart.wigg@gmail.com Member
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Hi, Attached is a photo of the head gasket that I recently dismantled. Engine overheating caused the head gasket to fail. I’ve not seen a blown head gasket before on an engine with liners, so I’m not sure what to expect, but this doesn’t look good! Next job is to clean the head up and check for true. Any other insight/advice very welcome. I’ve done a good few head gaskets, but not for this engine. I have been digesting Mr Engel’s advice pieces so I’m not coming to it cold. This is a LotusBits built 912 stroked to 2.2 with about 3 hours on it. Attachment: head gasket.jpg (Downloaded 79 times) Last edited on 01-16-2025 08:19 pm by stewart.wigg@gmail.com |
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stewart.wigg@gmail.com Member
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close up of head gasket Attachment: head gasket close up 1.jpg (Downloaded 76 times) |
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stewart.wigg@gmail.com Member
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another close up of other cylinders Attachment: head gasket close up 2.jpg (Downloaded 76 times) |
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stewart.wigg@gmail.com Member
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head looks ok? Attachment: head.jpg (Downloaded 77 times) |
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stewart.wigg@gmail.com Member
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block looks ok? Attachment: block.jpg (Downloaded 74 times) |
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stewart.wigg@gmail.com Member
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block side of head gasket Attachment: block side of head gasket.jpg (Downloaded 75 times) |
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vnavaret Member 
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Interesting failure. The pressure in each cylinder pushed the head gasket laterally, causing it to buckle. That to me says that the clamping force on the intake side of the gasket was inadequate to pin the gasket in position. I don't know what you may have noticed during disassembly (undoing the nuts on the studs) but it looks to me like the head nuts were inadequately torqued on the intake side of the head. This looks like an assembly error to me. Vance |
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stewart.wigg@gmail.com Member
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I don’t have concrete measurement, but I was a little surprised how easily it was to undo the head nuts. The cam carrier bolts seemed tighter! The head and block look ok to you? Might the failure potentially cause an issue with the liners? |
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noomg Member
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Stewart, You picked a good source for information, I don't know of anyone who knows more about that motor than Tim Engle does. If he doesn't chime in here you can get him on the Jensen-Healey Facebook page, he's the resident engine expert. |
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vnavaret Member
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stewart.wigg@gmail.com wrote: I don’t have concrete measurement, but I was a little surprised how easily it was to undo the head nuts. The cam carrier bolts seemed tighter! The head and block look ok to you? Might the failure potentially cause an issue with the liners? The liners are iron, so if the aluminum block edges look OK, then the liners are OK as well. The iron is much tougher than the aluminum. If the head nuts were easier to undo than the cam carrier nuts were, it was indeed an assembly error, with the head being under torqued. Save that gasket and take it back to the engine builder. Whoever it was, they screwed the pooch if the engine blew a head gasket after three hours. Vance |
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stewart.wigg@gmail.com Member
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Thanks Vance. The engine was built in 2010 and sat around for a long time before being fired up last year, so I think the warranty is expired! I’ll make sure the head is torqued properly when it goes back together - I’ve seen the recommended rain dance using a torque angle gauge. |
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Jh092 Member
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You might want to consider new studs when you put it back together. |
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stewart.wigg@gmail.com Member
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sounds like a good idea given I don't know the history of them or which type they are and therefore the torque/technique I should apply! |
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vnavaret Member
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Jh092 wrote: You might want to consider new studs when you put it back together. Having just gone through disassembly of my engine, this may be much more difficult than it sounds. Admittedly my engine sat around in the rain for a few years before I started disassembly, but those studs were a B**** to get out. And of course one needs to worry about breaking one off, which would really ruin one's day. I would say DO NOT put a breaker bar on there and lean into it. Double nutting them will not work, the force required will simply back the nuts off no matter how tightly you you install them. Instead use a stud puller and an impact wrench (NOT A BREAKER BAR!). They will not come out instantly, but letting the impact wrench hammer away will eventually loosen them and they will come out. Be sure that your stud puller is rated to accept an impact wrench. If you get a cheapie, the impact wrench will break it. One factor in your favor is that the nuts were not tightened in the first place, so hopefully the studs will not have been wound too tightly into the block. Fingers crossed. When (re)installing the studs, remember that they are installed finger tight, and no more. Vance Last edited on 01-19-2025 06:31 pm by vnavaret |
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stewart.wigg@gmail.com Member
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I got lucky and the studs came out very easily. New ARP studs on their way shortly with the nuts, grease and washers. I didn’t get so lucky with the head though, it’s no longer flat :( |
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vnavaret Member
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If the head is toast, I have a spare that's for sale. Let me know. |
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stewart.wigg@gmail.com Member
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I got a copy of an excerpt which documents the allowable tolerances for head warp. The head appears to be well within tolerances: Longitudinal 2&3 0.0025" (0.06mm) 1&2, 3&4 0.0025" (0.06mm) Transverse Rear less than 0.0015" (0.04mm) Front 0.0015" (0.04mm) So looks like I don't need to machine the head. However, I also checked the block. Longitudinal 2&3 Lower edge 0.002" (0.05mm) 2&3 Upper edge 0.012" (0.3mm) Transverse No discernable warp I don't have any numbers for the block tolerances, but the longitudinal distortion at the upper edge looks concerning. Anyone know the tolerances for the block? Attachment: head tolerances.PNG (Downloaded 47 times) |
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stewart.wigg@gmail.com Member
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Tellingly, the block distortion coincides with where the head gasket seemed to let go. |
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DonBurns Member
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One thing to look at, is the liner nip. When I had engine for 15800 rebuilt, I warned them about the nip (liners higher than block). When I came in to inspect the block before assembly, I saw that they had decked it flat. Since JH head gasket isn't raised around cylinder openings, I think that nip is important. Had to argue with builder to get them to write an NC program for their mill to cut block back to provide the nip. They were not happy with me - totally believed it was unnecessary. Probably nothing to do with your issue (probably a nut torque issue as suggested) but something to check. Also there is a lot of info on this forum about studs and torque requirements with the new style gasket. |
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stewart.wigg@gmail.com Member
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Update on this saga. Having disassembled the head, my builder found that the head had been machined too much and had broken through to the water jacket then.. epoxied. So the head is toast. Still waiting for the verdict on the block. |
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redracer Member
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Just read this--Sorry to hear about your problem. After 45+ years of working on these cars, I too have my first blown" head gasket, but not for the reasons that seemed to have happened with yours("too loose on the head nuts_. Anyway, some engine work had been done on this car, although the head nuts were "over-torqued"(O.E.M gasket--needed a breaker bar to loosen them!). Cylinder #4 appears where the "leak" is, and would "boil" the coolant after the engine gets warmed up. I haven't checked the nip yet, but the gasket shows it did seal all around the liner top. btw, I also have some "extra" heads as well bruce/redracer |
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vnavaret Member
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redracer wrote: Just read this--Sorry to hear about your problem. After 45+ years of working on these cars, I too have my first Bruce: Another interesting failure. Head nuts over torqued? Any idea if that might cause a failure? Boiling the coolant after the engine warms up is definitely a symptom of a head gasket having expired. I suppose the block and liners may have been decked flat, so the gasket had inadequate clamping force on the liners. Might explain why the nuts were over torqued - to compensate for the lack of clamping force on the liners? Overheating or perhaps burning coolant may have tipped the builder off that the gasket wasn't clamped adequately, so he tightens down the head nuts to avoid having to remove the head. Or perhaps the gasket failed immediately, so he puts in a new gasket and wants to make sure it doesn't happen again. Hmmm. Well, let us know what the nip looks like. That may hold the answer. BTW, I also have an extra block should you decide you need one. But then I would imagine you have a couple in your parts stash already. =:-) Vance PS: After this discussion, I verified that the nip is indeed still there on my engine, and when I took the engine to the machinist to get the new pistons fitted, I did not check the box next to "Deck the block" on the work order. Problem avoided! Last edited on 02-15-2025 06:48 pm by vnavaret |
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stewart.wigg@gmail.com Member
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So looks like the block is a gonner too. I was sold a bill of goods and this engine is definitely NOT a fresh LotusBits build. Scored crank, epoxied head, epoxied oil pick up, broken rings.. So I'm looking at a complete engine rebuild. If it was street car I'd have a go myself, but its for a racer so needs to be bullet proof (if that's possible!). Anyone have a recommendation for a specialist builder in Canada/US? |
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Art DeKneef Member
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Well, depending on where you are there is of course, Redracer. Bruce is in Brookhaven, Georgia, US. Then Barry Spencer in Livermore California. Mike at Delta Motorsports, Phoenix Arizona. Though I think he is booked out for several months from a discussion I had with him recently. Best to check. There was Judson Manning, but I don't know his current status. Last I heard he was in Tennessee. |
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