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Mazda 2.6L \  1991 b2600i engine head removal

1991 b2600i engine head removal

Mazda 2.6L Mazda Engine Mazda Tech
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replies 14
following 3
 
ssvashon5   +1y
I bought my B2600i last fall for a good price as it had cylinder head water issues, blowing steam-smoke in exhaust,
I love these trucks as they're easy to work on relatively, practical and affordable.
I verified this truck has 57,000 miles with carfax, and based on all the condition of everything I'm sure its legit.
So last week I took the head off finally with much of my sons help. We've sent the head to the machine shop for pressure testing, warp test and resurfacing if needed.
My main question is when I drained the oil from the pan there was about 1-2 quarts of coolant that came out first.
Someone told me I should remove the timing chain cover ( and of course that means oil pan comes off). They said I need to make sure there isnt a leak from the timing chain area into the lower end. he said apparently the chain can lash and damage enough to cause a water leak.
The chain is in great condition and I dont want to take more off than needed. Anyone have any wisdom on this?
Could the coolant have gotten into the lower end another way?
with the head off the coolant chambers seen from above on the block all look to be holding coolant still.
Thanks!
ssvashon5   +1y
Head removal so far
post photo
courier   +1y
i would have said do a compression test before it was all pulled apart. Its a great aid to trouble shooting, you see which cylinder(s) affected, and if bad rings or a head issue by pouring thick oil into a cylinder. Also a leak down test is very good, i dont have experience with however.
Re the timing chain issues described, i would get a copy of the Hayes manual for the engine, read carefully. I have fixed nearly all my dramas based on these manuals. Is also good to get 2 different manuals for the same engine, they say things differently, which is good for understanding how the machine works.
As with all these engineering related projects, getting an accurate diagnosis is often the hard part! i like to pull lots of stuff apart for inspection and cleaning, but only when i know where i'm going with it. Sorry this is all a bit general.
Cusser   +1y
Try to get a copy of the electronic version of the factory service manual (1992), better than Haynes or Chilton. Also consider posting your questions at MazdaTrucking.com for more opinions.
ssvashon5   +1y
Thanks all! I did a compression check before taking the head off and 3 of 4 cylinders were about 140 lbs and # 3 cly was about 110.
I'm waiting to hear back from the machine shop tomorrow on the head pressure, vacuum and cleaning check.
Post was last edited on May 26, 2016 03:05. This post has been edited 1 times.
courier   +1y
Gidday, yes well done on doing those compression tests, they agree with your photo; the #3 cylinder is stuffed and has big droplet of water sitting in it. So it may have done its head gasket? or the head is warped somehow? Will be interesting to hear what the machine shop guys say.

To answer your above question, i'd be tempted to remove the water pump for inspection. Heard (generally speaking) that some engines can get cracks or holes in the water pump housing which leak into the oil system. This could cause a leak from the timing chain area into the lower end? i'm not familiar with these engines at all however. I'd say if the chain was lashing it would make one hell of a noise, that you'd know all about, and the engine wouldnt run for too much longer. Also wouldnt you remove the pan for cleaning, to get all the residue from the water out?

And generally, what caused the damage to the engine initially? did it overheat? how badly? you'll need to find out why it happened eg leaking water pump, leaking hoses etc etc. I wrote off a nice FE3N engine few years ago, had a leaking radiator hose, at idle it was fine, it only leaked at above 2000rpm. Head gasket blew and bad cracks in the head, totally cooked so no hope of saving it. I was advised that when you overheat badly the alloy head will be annealed (ie softened) as aluminium is a soft metal, in the factory they heat treat it to make it strong enough to work in an engine. Potentially you can put an engine back together, then have issues down the track as the head has gone a bit soft. In my case i got another complete engine from the dismantlers, put it in, kept the blown one for spares. Also badly overheated can damage rings and do strange things to the block people told me.

will be good to hear how it all works out!
ssvashon5   +1y
Got my rebuilt head back today. New main head block. Waiting on gaskets from usps Monday.
Also Courier thanks for your post.
Based on 57k documented miles I'm going to pull oil pan and timing gear cover off to inspect those at least.
I think the engines good. I did get old head back and can see the crack in #3 cylinder. It goes from head surface into valve seat area, so #3 was problem.
Inspecting timing chain area and if it looks good then putting it all back together. Thanks all.
post photo
Post was last edited on Jun 11, 2016 03:06. This post has been edited 2 times.
ssvashon5   +1y
So after cleaning the tining chain cover I'm seeing hairline cracks , see photo.
Can't I put sealant or JBWELD on this?
Timing was fine and no other issues other than cracked head before teardown.
geterdun   +1y
Was the truck running before you disassembled it? If so the water would have mixed with the oil and been milky oil at draining. Any chance this is just water that got in the pan during disassembly? Most likely if you did not drain the radiator before pulling the head, especially if the water was separated.
There is a water passage across the head between three and four. My first b2600 head cracked there during a severe overheating. Be sure you have water flow through this passage all the way from where it enters the head to the 5/16" hose where it connects at the rear on the passenger side to a pipe after reassemble. Be a shame to crack another because of this unresolved blockage. Only hope to seal would be a block sealer, get it from NAPA, in this instance of product purchase, think it is KB block sealer? Goes in the radiator.
Always the option to have the block magnified to check for cracks, if in doubt. It is a chunk of money to invest to end up at same place.
ssvashon5   +1y
Thanks all. I git the engine started yesterday after the new head installed. Started right up.
Now I've got some noisy lifters I need to figure out.
I have new oil but due to old oil that was in engine I may need to change it several times to quiet it down??