Been having problems with blown head gaskets. Ive been using FelPro blue stripe head gaskets ..... the supposed kind that dont require sealing nor re-torquing. Twice now I've blown into the cooling jacket/passages. The second time I over-torqued and it still blew. (all the srufaces are FLAT). These 'blue stripe' gaskets seem 'awfully hard' ... am I 'missing something'?
Whats the best out there these days? I usually prefer to seal with aircraft grade permatex and dont mind retorquing until the cows come home. Im certainly NOT happy with these "blue stripe Fel-Pros". Whats your favorite 'brand' these days.
Well Rich, I actuall PREFER FelPro gaskets. BUT....... you have to be absolutely sure that the surfaces are straight and flat....... BOTH surfaces....... Over torqueing is actually worse than under torqueing the bolts........ overtorqueing will cause the cylinders to not be round anymore and cause all sorts of other flex problems. FelPro gaskets are actually thinner than other gaskets.....even the stock over the shelf gaskets from the dealer and or other brands....(not too knowledgeable here, just know they are a bit thinner) Sooooo....... make sure you are FLAT make sure you are FLAT...... make sure youi are MACHINE SHOP FLAT.... DON'T Over torque the bolts..... Follow the Torque pattern exclusively of the head bolts they have to be torqued in a certain order......THIS IS important try adding some lock tite (high temp) to your head bolts, and adjust the torque for oiled threads..(ANYONE????) Make sure you are using NEW head bolts Try a generic gasket.....which is thicker...... It DOES sound as if you have a issue with Flatness or straightness around where ever you are blowing, assuming it is in the same area............ overtorqueing could be an issue..... Is your torque wrench reliable??????? Robb
To add a little to this, make sure that the threads on the bolts and in the block are clean too. It doesn't take much crud to really throw the torque readings off. Also, do NOT put any sealer on these gaskets. I may have misinterpreted your post, but sealer on these gaskets is a no-no. If the head was milled, make sure the surface wasn't machined too smooth. This will cause problems as well. The finish should be about 100 RMS, which any competent engine shop should be capable of checking.. Be careful using oil on the bolts when you tighten them, this may cause you to over torque if you don't adjust the readings to allow for oil on the threads. clean the surfaces and make sure there is no gasket material left on them when you put the new gasket on. then clean the surfaces with lacquer thinner, or some other solvent that doesn't leave a film. Don't use gasoline. The non chlorinated brake cleaner works good for this, but make sure you don't get it on anything that has paint on it, because it will ruin the paint. One other thing you may want to check is to make sure the head sits against the surface of the block without the gasket in place. On rare occasions the locating pins will not let the head slide on completely and could cause this problem. Last, do not over torque the bolts, this can damage the sealing ring in the gasket. As far as the Fel-Pro gaskets are concerned, I have used them for years without any troubles, so I would suspect the issues are somewhere else.
Chris
"Robb S via CarKB.com" wrote in message news: snipped-for-privacy@CarKB.com...
THATS probably it...... near the area of the blow out. (now why didnt I think of that earlier). Thanx I always use NEW bolts, and properly oil them and run a bottom tap in the bolting bores, I also measure the bolt length to ensure that they are not 'bottoming' out, etc.
You guys are 'great'.- Many thanks, much appreciated.
Without having an engine manual here, I don't know if you are supposed to oil the bolts or not. It varies from engine to engine, so make sure you're doing the proper procedure. Oiling the bolts when they aren't supposed to be oiled will cause a serious overtorque, and also, not oiling the bolts if they are supposed to be oiled will cause the bolts to be undertorqued. There is a chart and a short explanation about the differences in torque specs dry, with oil, and with assembly lube here:
Hey Chris, Yes, I was referring to loctite, but only for the bolt threads......never for a gasket..... But......I would think that if you use locktite, becase the threads are wetted and not dry, an adjustment on the torque should be made for the wet threads.......Not sure if this should be oil, sealant adjustment??? Wasn't looking at a manual when I wrote the post...... Thanks for picking up all the other stuff I missed......GREAT input.....
Found the problem !!!! Found it in a Service Advisory update 1989! Engine is a 2.8L, that Ive rebuilt and cammed, etc. etc. etc. Everything is flat, etc. etc.etc. There in the small print of the service advisory in a borrowed shop manual: ...... head bolt threads shall be coated with RTV !!!!!!!!!!!! Yeah OK, the outboard bolts do actually penetrate the water jacket and the head bolt threads DO need to be sealed .... just like an old fashioned studded engine. Last two times of extensive engine work with (head gasket replacement) I just guess I was 'lucky'. I made up a 'jig' and pressurized the outboard bores .... yup, they are directely connected through to the cooling loop. After several other previous gasket replacements (dry) .... I found the friggin problem .... thanks for all your kind advice - It at least got me looking in the right direction.
MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.