mickeyw Posted July 7, 2014 Share Posted July 7, 2014 My 110 has a 3.5 15G engine, that is in need of a little attention due to a suspected head gasket failure. Symptoms are a splutter on start-up that soon clears, a really badly corroded plug in no.1 cylinder, moderate water consumption and it pressurises the cooling system very soon after start. Other than that it run really smoothly with no tappet or other rattles, doesn’t seem low on power (this is only a 114bhp version), and doesn’t overheat. It is painted that lovely duck egg blue that is used on military engines, and carries a plate saying it was remanufactured for ABRO, back in 1997. Since then it has done around 75k miles, according to the paper trail that came with the truck. I’ve removed the head on the odd numbered bank, and there is a light amount of coke, but no obvious signs of the tin gasket having failed. No steam cleaned piston either, although tbh the water leak wasn’t that bad, however I wanted to rectify things before it became a reliability problem. Having degreased the head I removed the valves. The inlets look fine, but the exhausts are quite burned. These valve pics are after I had cleaned them of crud and coke. The rocker gear looks in excellent shape with very little wear to the rocker pads or valve ends. Even the hydraulic tappet faces look near new, and the cam lobes look quite unworn. Now before someone says why bother with this lower output engine? I shall just mention that it is intended to fix this up and run it until I get the 3.9 that is waiting in the wings ready for fitting. One concern I have is that having bought a head gasket set (a composite set) is that replacing the tin gasket with the thicker composite one is going to drop the compression even lower than the already low 8.13:1. I cannot see evidence (machining marks) that the head has been skimmed previously. I did find that the rocker posts have shims under them (1.20mm). I’ve never found these shims in any V8 I've opened up before, although I am aware they exist and the fact that they are used to adjust tappet preloads. But what might their presence indicate? Previous skimming of something, or not necessarily? So, points I’d like confirmation of – If I fitted a composite gasket, it would affect the rocker preload, thus requiring a change of rocker post shims? From various reading there is approx. 0.5mm difference in gasket thickness (tin vs comp) when compressed. From a perspective of a quick budget fix I would be better of using tin gaskets again, rather than suffer a loss of compression ratio, and/or need to machine any faces to compensate? The exhaust ports and valves need some attention, but I don’t really want to spend on having them refaced, so could I get away with some heavy lapping? From past experience this degree of lapping can take quite some time Your collective knowledge and expertise are welcome gents. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 7, 2014 Share Posted July 7, 2014 Composite will work fine, worked fine for me for ages on the 3.9. Quote Link to comment Share on other sites More sharing options...
JeffR Posted July 7, 2014 Share Posted July 7, 2014 I used composite gaskets on my 8.3:1 V8 and to be honest, can't tell a difference. I suspect the low cr V8 is a somewhat forgiving engine. Quote Link to comment Share on other sites More sharing options...
Jamie_grieve Posted July 7, 2014 Share Posted July 7, 2014 I agree, use the composite gasket, the hydraulic tappets won't mind. When you say the cam lobes don't look very worn, do you mean not worn at all and look brand new? If not I'd start there or be looking at fitting the 3.9 sooner rather than later. Use a cordless drill to lap the valves in, the ones you show have plenty of meat on them. Use the drill just like a stick and don't go too fast or let it squeak. Keep plenty of paste in there, oil the guides and you'll be done in no time. Some people might be in horror at this but it's fine. Check your timing, it looks like it's been running a bit hot and pinking. Did you do a compression test? Quote Link to comment Share on other sites More sharing options...
Team Idris Posted July 7, 2014 Share Posted July 7, 2014 I've got an export 3.5 from a disco with composite head gaskets on it. I suspect you loose top end power rather than torque if you lower the compression. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 8, 2014 Author Share Posted July 8, 2014 Had a bit of a clean up of head #1 last night. Drill with wire brush to the combustion chambers, bit of lapping of valves with fine paste, clean up of gasket face and so on. There seemed to be a fine layer of clear varnish on the face of the head, like a really thin layer of silicon. Hope to gawd it wasn't! It lifted off easily with a gasket scraper. The pitting to cylinder #1 is quite notable. I believe the chap I bought this from had been driving with this gasket leak for quite some time, and probably without understanding what was going on. Whoever last cleaned the face of this head used some very coarse abrasive. Note the deep scratches in the surface. I used 320 grit paper wrapped around a large steel parallel, and lubricated with WD40. This relatively polished the surface compared to the house brick marks already there. After my cleaning there were still witness marks from the tin gasket between the chambers. (This is cyls 1 & 3). Holding a straight edge over them makes the irregularity look scary, although in reality it seems to be less than a thou' Between 5 and 7 looks worse but again the marking aren't actually THAT deep. Given the undulations and the confidence of posters above, I feel composite gaskets stand a better chance of coping with sealing than tin ones. The valve lapping went pretty well. The inlets were pretty good anyway, and the exhausts seemed to clean up with less effort than I had expected. Use of my Gunsons Eezilap helped. Quote Link to comment Share on other sites More sharing options...
CwazyWabbit Posted July 8, 2014 Share Posted July 8, 2014 Maybe the previous owner had tried Quote Link to comment Share on other sites More sharing options...
Team Idris Posted July 8, 2014 Share Posted July 8, 2014 Time to get it skimmed I think, unless you are super sure that it is flat via and engineers straight edge? A lot of castings change shape with age anyway, as they let go of their internal stresses. Mcormic tractors used to have no liner protrusion one side and 4 though the other as the block leaned over with age. It just seems a shame to do all that work and risk it with uneven gasket compression Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 8, 2014 Share Posted July 8, 2014 Yeah I would skim them looking at that... Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 8, 2014 Author Share Posted July 8, 2014 What is a reasonable price to pay for a head skim these days? Quote Link to comment Share on other sites More sharing options...
Jamie_grieve Posted July 9, 2014 Share Posted July 9, 2014 I've put way worse than that together with no dramas. If it was your only engine I'd agree with the rest and get the heads skimmed but given you have a 3.9 in the background I'd just horse it together as is with what you have though some of the valve seats need lapped in a bit more. You need a solid line al the way around. No point in polishing a turd and throwing good money away. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 9, 2014 Share Posted July 9, 2014 You can get a pair round here done for about £30. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 9, 2014 Author Share Posted July 9, 2014 So for that kinda £, it's worth doing. The gasket kit cost more... With my normal rate of project progress I do need this engine to last until I remove it, not just for 6 months Got the second head off last night and found similar to the first regarding surface conditions. I'll post some pictures later. I watched your video link Barry. Apart from being a rough surface, that probably gives a pretty flat result. If one were to finish with finer paper... Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 10, 2014 Author Share Posted July 10, 2014 Rung up a local engine machining place this morning - he wants £50 per head for a skim! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 10, 2014 Share Posted July 10, 2014 That's... not cheap at all. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 10, 2014 Author Share Posted July 10, 2014 Well as I said - the second head didn't look any better than the first. I did find that the gasket appears to be coming apart though, it's like this on 3 cylinders. +0.020" pistons - seems it has been rebored before Tappets haven't taken on the all-too-frequently found dished end. Quote Link to comment Share on other sites More sharing options...
Cynic-al Posted July 10, 2014 Share Posted July 10, 2014 Head skim around here is £30 - £35 + vat per head. Quote Link to comment Share on other sites More sharing options...
hangover Posted July 11, 2014 Share Posted July 11, 2014 Composite gasket will take up any imperfections in the head surface so as long as they are flat i'd just refit, done 2 x 3.5's without head skimming. One done at 150K and sold with 270K, other done at 260K and sold at 275K , pity it wasnt as easy for a 300TDI - that required a new head. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 14, 2014 Author Share Posted July 14, 2014 Well, a trip to the local machine shop on Friday saw me coming home with two flat faced heads and an empty pocket. Job was done by a chap well past retiring age, and with a real old skool horizontal mill (sorry I didn't take any pics in there). He runs a while you wait service and was only 5 minutes from home, so I kinda justified the £100 bill to myself that way. Both heads were a little out, but the leaky one wasn't the worst. End to centre to end saw only 0.004" TIR, but the heavily indented areas between each end chamber and its neighbouring took just over 0.005" to clean up. This evening's activity has involved more valve lapping, a thorough clean of all the threaded holes and general readying for refitting the valves. I also have one exhaust manifold thread to Helicoil tomorrow. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 18, 2014 Author Share Posted July 18, 2014 Went to refit the heads last night, and found a few feaures on the composite gaskets that I don't understand. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted July 18, 2014 Share Posted July 18, 2014 That's very strange! Pretty sure no V8's have bolts there! Quote Link to comment Share on other sites More sharing options...
Team Idris Posted July 18, 2014 Share Posted July 18, 2014 There should have been some there though I blame Buick ! To be fair, if they had put some there, the heads wouldn't drain and the push rods would be really tight. It is a fairly minimalistic engine for it's era. I was impressed. (Except the chiselled out valley drains) Quote Link to comment Share on other sites More sharing options...
Rangie46 Posted July 18, 2014 Share Posted July 18, 2014 Them gaskets do look wrong defo no holes there, what make are they? These are erling, upside down thou in this pic Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 18, 2014 Author Share Posted July 18, 2014 The gaskets are from a well respected company. I'll give them a call on Monday just to check what's what. I've had quite a few V8s apart, and not seen gaskets like these before. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted July 21, 2014 Author Share Posted July 21, 2014 Said supplier of gasket kit, and well known engine remanufacturer has confirmed these are the same design of gasket they use on all their work. Reassembly will commence Quote Link to comment Share on other sites More sharing options...
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