Brought a recon 1600 tp a few months backs and am having a lot of problems First time I ran it up it nearly immediately dumped its oil and seemed to come from the cooler. I dropped the engine and replaced the cooler only for it to happen again. I noticed that it actually blew the seals between the oil cooler mounting plate and the cooler. It went back to be rebuilt only for exactly the same thing to happen again only this time blowing the cooler itself. I'm at my wits end and considering putting the new top end onto my old bottom end which seemed fine. The engine builder says he spent ages checking over the pressure relief valve (which was a re-used one) and is at a loss and had proposed to use a different case. I won't go into details but I've had enough now after nearly 5 months of this and want to sort myself. So before I make one good engine out of two do you guys think it could be something else or is it worth trying a brand new pressure relief valve? It seems to be too much compression.
No haven't done compression test and stand is just the bog standard one. Engine is out and stripped now.
I'd put money on the front relief valve not working. Its main job is to bypass the cooler when the oil's cold.
first sign of excessive crankcase pressure is usually oil from the crankcase seal, so if this was fairly clean, then it does sound like the relief side of things was a fault (but presumed checked by the engine builder) or a plugged gallery. hopefully one of the engine gurus will be along to give a more informed answer. I know I had a 12 month old Suzuki DR 350 (4 stroke) seize up....pulled it apart, couldn't find anything whatsoever wrong with it....all tolerances, rings, bearings etc. spot on. Built it back up and completely by chance noticed a tiny bit of metal in one of the oil feed tubes from the cylinder head to the crankcase...pulled it with some pliers and a great long spiral of swarf came out....been starved from new....warranty had run out Anyway...hope you get to the bottom of if...let us know what you find, if anything
I think he's suffering from excessive oil pressure, not crankcase pressure. Did oil pressure actually burst the oil cooler? If yes, I'd say it's valve-related: maybe jamming in the bores or wrong springs. In a dual-relief case, there're two valves. The one at the pulley end bypasses the cooler when the oil's cold/thick and high pressure, to prevent the soft aluminium cooler bursting. The one at the flywheel limits the overall oil pressure to about 42psi (3 bar): you'll never get higher pressure than this. Poss that one's not working, causing oil pressure to rise higher (which it could potentially do). Fairly easy to replace, but the case bores need to be in good shape. Another poss is (as above) one of the oil galleries (maybe on the bypass side) is blocked.
I think blocked oil gallery was mentioned as a possibility hence why he was planning on changing the case this time. I had thought about just buying some new pressure release valves and springs to try as apparently the ones in there are re-used but having now looked at them on the net I see they are very basic. I think he said after the first rebuild one had gone up and lapped over and got stick or something hence why he had spent a long time cleaning and smoothing them so they ran freely. As for oil I initially started with the jk stuff the. Swapped to 15/40 I think. I don't know about oil pump size. Seems he doesn't bench test the engines before sending out Oh and I notice the case was a Mexico one if that makes a difference. From the state of the chipped fins around the sump I think it had a hard life before I got it.
You'd have to pull the cover off and measure the gear depth.. Really does sound like a stuck relief valve, or a blockage somewhere, but if he's put a 30mm pump in that won't help matters... Stock oil pump is 24mm, so cold oil pressure will be a lot higher with a bigger pump!!
Right thanks for that will check that. I'm thinking it may be best to stick with my old bottom end which I recently did 2000 miles in and use the new top end. Sadly lesson learnt with supposed engine builder. Will be more careful next time
Be careful putting the new top end on the old bottom end... the increased friction of new piston rings, and a higher engine compression (due to the new rings) can lead to premature wear on the big ends and main bearings... It's good practice to replace the bearings even when doing just a top end build!!
You're easily pleased Valves/springs easy & cheap to replace - the real b*gger is undoing the big "screws" that hold them in! May need to file a bit of steel bar to act as a gigantic "screwdriver".
