Rebuilt Cylinder Head v. Machine Current

[coldday]

1999 Isuzu Rodeo S (2.2L I4, DOHC)

timing belt snapped, repair shop says no compression (they put a new timing belt on). can't afford them to repair (1600.00 est.) so going to take a stab at it w/ my dad.

question: anyone have any experience with rebuilt heads vs. taking my orig. head in and having a machine shop repair? Cylinder Heads Int'l http://www.headsonly.com/isuzu.htm has a head for $425 + $20 shipping and includes free shipping return for my busted head to them, and a 12 month warranty. Machine shops quoted me (estimate w/out seeing my head) labor of $372 dollars + parts, valves running from $7-$15 each. Seems like buying a rebuilt head would be better deal?

I've yet to pull the head (this Sunday), anyone have any tips would appreciate it. Bought a Haynes manual which I'll read tonight.

ALSO; i'm not confident i know why the belt snapped, suspect tensioner (repair shop told me the tensioner and pullies should probably be replaced), but when this all happend, CEL and Oil Pressure light was on. Is the oil pump a possibility?

Added: Have 137k currently. Timing belt was replaced at 43k by dealer due to recall - seems they replaced the tensioner too at this point, then I had timing belt and water pump replaced at 101k.

Thanks.

[redbug]

Hello,

I would want to know why this failed before I forked over all the money for a new head.... Were you out of oil? How old was the oil? If you get the valve cover off you may see that the cam bearings are tight, due to lack of oil, which would surely cause the belt to snap..... Also, does the new head include good cam and bearings??? $425 sounds better because it comes with a warranty...

How is the oil pump driven? On the 6 the pump is driven by the crankshaft... Could the 4 drive the pump via the belt????

Not much experience with the inline 4, I had a V6 1995... If you had the V6 I would tell you to pull the engine to do the repairs.. But, since you have the 4 it should be easier... I saw a posting on the internet where a guy gave a step by step pictorial history of his inline 4 isuzu valve job... Can't find it now...

Some engines drive the belt tensioner via oil pressure, not sure about the isuzu 4...

Yes, I would replace all components on the belt, do you want to risk this happening again?

Good luck.

[coldday]

was due for an oil change, never had a problem w/ leaks or burning oil.
was on an uphill incline where i pulled over. dipstick had very little showing on the red tip, had some oil brought to me and put 1/2 quart in and it was fine at that point, so seems the oil level would have been fine?

will check the manual (not yet arrived) re: the oil pump location/drive.

repair shop assistant was telling me the tensioner seemed to be the reason it failed, and recommended i replace it and the other two (which I'm not sure if they're tensioners or just guide pullies). figured i better replace them all.

rebuilt head comes w/ cams;
http://cgi.ebay.com/ebaymotors/ISUZU...35305719QQrdZ1

thanks!

[JustSayGo]

Your timing belt recall would have resulted from a large number of belts failing during to short of a service period, more than likely while under warranty and an expence to the manufacture. I suspect that your engine requires a stronger belt than the original which the recall campaign addressed. Make sure you use the better quality belt. Did your engine overheat prior to the waterpump replacement repair? If so the cylinder head may have warped a little and caused the cam to bind in the bearings and as redbug is conserned, made the cam bearings tight, making the cam more difficult to turn by a belt that may have been the lower OEM quality.

One half quart low is not a problem, 2 1/2gts would be. When you receive your repair manual, I think you will find that your oil pump is driven directly by the crankshaft. Timing chain tensioners usually use oil pressure to push a rubber shoe against the chain with ratcheting teeth to hold the shoe in adjustment when there is no oil pressure. Oil on timing belts causes severe deterioration so timing belts use springs to adjust belt tension and are held in place by a bolt(s). Timing belts are often packaged including tensioner kits. Check for prices and quality on all the parts from the cylinder head exchange place. Both options are rebuilt heads.

[coldday]

i had the water pump replaced because a friend told me it was good thing to do since the tbelt was off already. added $222 to the job. figured with 101k not a bad idea. the repair shop that did this and the t-belt did not replace the tensioner. tbelt at 101k cost was $49 so maybe a cheapo causing me all this grief? the belt a diff. shop just put on to replace the busted one at 137k cost me $65 bucks, so maybe this new one is better quality?

anyway, hoping the pistons are not damaged and that it was cheap belt/bad tensioner (or maybe the belt was on too tight???)

i recollect an odd whirring noise had started maybe a week before the belt broke, that would cycle, "whirrrr, whirrr, whirrr" and didn't seem to be tied to rpm. but seemed it would go away after a bit - warm up or so. any ideas if related?

thanks much for all the input.

[JustSayGo]

Timing belts, or more likely the bearing in the tensioner make a whirring noise (good discription of the sound) when the belt is too tight. Was the oil pressure light on while the engine was running just prior to dieing? The oil pressure light and CEL should both come on when the engine stopped. The differance in price of the two belts also may easily have been for the same quality belt.

[coldday]

i only noticed both lights (cel/oil pressure) once i was on the side of the road, they'd both stay on w/ the key was left on. i don't know if they were on while i was driving, but i didn't notice them.

when i had the 101k belt changed i thought it was noisier than i ever remebered so i took it back and they readjusted the tension on the tbelt, but didn't seem to make a huge difference.

but this new whirring noise sorta pulsated or cycled. maybe belt was always too tight since 101k? maybe ruined the tensioner being too tight?

was going to take it in within a few days because it needed oil change anyway but procrastinated too much, not sure repair shop would have caught it though, but who knows.

i moved in march to a location where i have to climb from 1800' el to about 3200' el to get home and i can't say i took it very easy on the car maybe that abuse combined w/ too tight a belt just couldn't take it...

thanks for the reply.

[redbug]

If the engine is not turning, you won't get oil pressure... Sounds like from what you described you did not run out of oil... Were you deep into some water off road? This will affect the timing belt pulleys. I believe your mechanic is right, probably was the tensioner...